The lipids have a majour role in the intiation step of atherosclrosis, thereof it’s a main componant of lipoproteins which can (in different methods) have a modification and then will have a changes in its receptors on cells, espacially artries wall. The last investigations in recent yeares take its care with the biological effects of wild aromatic medicinal plants as hypocholesterolemic agents, and its ability to prevent the action of atherosclrosis. So that these plants acting (with its nutral active componants) as antioxidants to decrease serum cholesterol and avoiding atherosclrosis.From this view the approximate chemical composition of Pulicaria incisa, Diplotaxis harra and Avicennia marina were studied and the results can summarize as follows:-1- Total carbohydrates were 52.48 %, 41,18 % and 41.66 %, crude oil were 0.44 %, 1.22 and 1.8 %, crude protein were 11.58 %, 7.84 % and 6.05 %, crude fiber were 25.8 %, 15.6 % and 16.3 %, total ash were 13.1 %, 24.6 and 16.8 %, for Pulicaria incisa, Diplotaxis harra and Avicennia marina, respectively.2- The investigated oils fatty acids composition was studied. The majority of fatty acids were unsaturated fatty acids (53.9 %, 83.48 % and 55.01 %), while saturated fatty acids (mainly, palmitic acid) were about (18.79 %, 10.37 % and 21.28 %) of the total fatty acids, for Pulicaria incisa, Diplotaxis harra and Avicennia marina, respectively.The free sterols content and composition showed most of sterols in Pulicaria incisa, Diplotaxis harra and Avicennia marina. Oils contain 50, 30 and 70 g sterols /kg oil, respectively. Unsaponifiable matter were (70, 60 and 120 g/kg Oil), respectively. Tocopherols content was 20, 18 and 29 g/kg oil. δ- Tocopherol was the major component which was (19.99, 18 and 29 g/kg oil) in Pulicaria incisa, Diplotaxis harra and Avicennia marina, respectively.3- The preliminary phytochemical screening showed that the studied plants were contain all tested flavonoids execpt Pulicaria incisa and Diplotaxis harra which were negative in flavonone and/or flavonols. Cardenolides was investigated and it was found in Pulicaria incisa and Avicennia marina and absent in Diplotaxis harra while desoxy-sugar were found in all studied plants. Anthraquinone glycoside was found in Pulicaria incisa and Diplotaxis harra while it was absent in Avicennia marina. Saponines was present in Avicennia marina and absence in Pulicaria incisa and Diplotaxis harra. Catechol tannins were found in all studied plants while gallic acid was found only in Diplotaxis harra. Catchine was absent, while, sterols and / or triterpenes appears to be found in all the three studied plants. Oxidases enzymes were found, while alkaloids and / or nitrogenous bases were present in Avicennia marina only and absent in Pulicaria incisa and Diplotaxis harra.4- Alcoholic extracts of Pulicaria incisa, Diplotaxis harra and Avicennia marina were investigated for total, free and conjugated polyphenols. The data showed that Avicennia. marina was (4.5 %, 0.84 % and 0.949 %) for total, free and conjugated polyphenols respectively, while Pulicaria incisa was (2.4 %, 0.64 % and 1.79 %), respectively and Diplotaxis harra was (0.95 %, 6.8×10-4 % and 0.949 %) respectively. The results of the thiocyanate antioxidant assays of Diplotaxis harra was (67.4%) and the lowest value was for the extract of Avicennia marina, which was (40%). The methanolic extract for radical scavenging activity (RSA) assays after (10, 30 and 60 min.) were (81.2 %, 80.92 % and 79.64 %) respectively for P. incisa while it were (79.79 %, 77.15 % and73.45 %) respectively for D harra and were (66.62 %, 66.46 % and 66.12 %) respectively for A. marina.5- A biological experiment was carried out using 30 male albino rats, which were divided into five groups after adaptation period (7 days). The negative control (6 rats) was fed on basal diet, while positive control was fed on a hypercholesterolemic diet. The treated groups were fed on hypercholesterolemic diets supplemented with 8 % of each of Pulicaria incisa, Diplotaxis harra and Avicennia marina, respectively. The experiment lasted for nine weeks. At the end of the experiment the body weight gain, liver and kidney functions and lipid pattern were determined.6- Rats fed on high fat diet showed the highest daily gain in body weight 1.89 ±0.3 g, while rats fed on Diplotaxis harra diet showed a highly significant lossing daily gain in body weight (-0.54 ±0.04 g). Addition of Pulicaria incisa to high fat diet in (8 %) highly significant increase in body weight gain, which increased from 37.01 ±1.21 g (in negative control) to 68.77 ±3.14 g (in Pulicaria incisa) after 9 weeks. Also, daily gain in body weight was increased from 0.58±0.02 g (in negative control) to 1.09 ±0.05 g. in Pulicaria incisa. The same trend was nearly shown for rats fed on Avicennia marina, where the body weight gain was increased from 37.01 ±1.21 g. to 48.5712 ±3.91 g and daily gain in body weight was increased from 0.58 ±0.02 g to 0.76 ±0.03 g for negative control to Avcennia marina, respectivily. Diplotaxis harra followed an opposite trend, where loss gain in body weight and daily loss in body weight gain were observed from 37.01 ±1.21 g to -34.62 ±2.8 g and from 0.58 ±0.02 g. to -0.55 ±0.04 g for negative control and Diplotaxis harra, respectively.7- Total lipids showed an increase from 400.71 ±7.06 mg/dl in negative control to 1551.12 ±43.76 mg/dl in positive control. By given the value 100 to negative control, the increase in total lipids was 387.09% for positive control. It was found that the addition of P. incisa gave the highest significant decrease in total lipid, which were 100 %, 387.09 %, 185.02 %, 98.67 % and 165.49 %, total cholesterol which were 100 %, 258.33 %, 135.93 % 81.81 % and 146.32 %, and triglycerides which were 100 % 559.91 %, 227.48 % 122.67 % and 244.03 %, for negative control, positive control, Pulicaria incisa, Diplotaxis harra and Avicennia marina, respectively. Other parameters also significantly decreased but in different degrees, so, HDL-cholesterol were 100 %, 51.53 % 85.89 % 60.41 % and 81.60%, while LDL-cholesterol were 100 %, 664.30 % 227.27 %,133.15 % and 274.94 %, and VLDL-cholesterol were 100 %, 5681%, 22.57 % 122.68 % and 244.12 %, for negative control, positive control, Pulicaria incisa, Diplotaxis harra and Avicennia marina, respectivily.6- The risk parametars for choronic heart deases were calculated. Chylomicronaemia were 100 %, 45.81 %, 59.68 %, 66.77 % and 57.09 %. TG/LDL-C ratio were 100 % 1091 %, 265.33 % 203.21 % and 299.79 %. HDL-C/Pooled lipoprotein cholesterol were 100 %, 19.78 %, 63.21 %, 70.79 % and 55.18 %. Atherogenic index were 100 % 1268.52 % 266.66 %, 218.52 % 333.33 %. Ratio of HDL-cholesterol/LDL-cholesterol were 100 %, 1302.3 %, 260.9 %, 222.7 % and 338.6 %, for negative control, positive control, Pulicaria incisa, Diplotaxis harra and Avicennia marina, respectivily.7- Most organs functions were improved and attained nearly to the negative control group. S.G.O.T. was 100 %, 260.88 %, 107.70 %, 142.81 % and 187.26 %. S.G.P.T. was 100 %, 226.07 %, 147.5 % %147.5 % and 153.57 %. S.G.O.T./S.G.P.T. ratio was 100 %, 115.83% 73.3 %, 97.5 % and 122.5 %. Serum total bilirubin was 100%, 227.27 %, 227.27 %, 181.18 % and 184.85 %, for negative control, positive control, Pulicaria incisa, Diplotaxis harra and Avicennia marina, respectivily.8- The protein fraction were done, so, the s. albumin were 100 %, 114.87 %, 78.44 %, 47.41 % and 78.88. Serum total protein was 100 %, 134.5 %, 108.55 %, 60.03 % and 115.98 %. Serum globulin was 100%, 171.08, 164.66 %, 85.53 % and 185.14 %, and albumin/globulin ratio was 100 %, 65.05 %, 48.92 %, 56.99 % and 42.47 %, for negative control, positive control, Pulicaria incisa, Diplotaxis harra and Avicennia marina, respectivily. Serum glucose was nearly returned the negative control it was 100 %, 127.32 % 92.68 %, 93.51 % and 92.38 %, for negative control, positive control, Pulicaria incisa, Diplotaxis harra and Avicennia marina, respectivily.9- Renal function was also done, s. uric acid was 100 %, 114.55 %,97.77 % 105.31 % and 98.80 %, and blood urea was 100 %, 177.61 % 162.2 %, 192.21 % 159.91 %, for negative control, positive control, Pulicaria incisa, Diplotaxis harra and Avicennia marina, respectivily.The present investigation concluded that, improving knowledge of the biological effect of wild medicinal plants would assist in the efforts to achieve the curing effect of these plants. Optioned data about its role as a hypocholesterolemic agent gives us valuable information about its biological role. P. incisa and A. marina plants can play a hypocholesterolemic role against hypercholesterolemia disease at rate of 8 % in diets. D. harra my do same effect but in lower doses. The possible role of such plants contents of active components, which may play as antioxidants, attack free radical, improve lipid pattern and organs function. So these plants considered as a new non-conventional supply for the pharmaceutical industries and for edible purposes.The approximate chemical composition of whole plant of Pulicaria incisa (Flea-bane), whole plant of Diplotaxis harra (Stink-weed) and leaves of Avicennia marina (Black mangrove) showed low oil and protein contents. The obtained data showed the total carbohydrates of Avicennia marina was high while it was moderate in Diplotaxis harra and Pulicaria incisa. The oils fatty acid composition showed increasing ratio of unsaturated fatty acids in all studied plants.The preliminary phytochemical screening showed that Pulicaria incisa, Diplotaxis harra and Avicennia marina were rich in falconoid, catechol tannins, cardenolides, desoxy-sugar, anthraquinone glycoside, saponines and gallic acid. Methanolic extracts of Pulicaria incisa, Diplotaxis harra and Avicennia marina were investigated for total, free and conjugated polyphenols. The thiocyanate antioxidant assay of the synthetic antioxidant butylated hydroxytoluene (BHT) was the highest value, while the methanolic extract of D. harra and butylated hydroxyanisole (BHA) was nearly the same. The lowest values were in the extracts of Avicennia marina and ascorbic acid.The methanolic extract for radical scavenging activity (RSA) assays after (10, 30 and 60 min.) were high for Pulicaria incisa, Diplotaxis harra and Avicennia marina, respectively.Body weight gain, liverand kidney functions and lipid pattern were determined, it was found that the addition of Pulicaria incisa gave the highest significant decrease in total lipid, total cholesterol, and triglycerides. Other plants also significantly decrease all these parameters but at lower different degrees. HDL-cholesterol, LDL-cholesterol, VLDL-cholesterol, chylomicronaemia ratio, TG/LDL-cholesterol ratio, HDL-cholesterol/Pooled lipoprotein ratio, atherogenic index and ratio of LDL-cholesterol/HDL-cholesterol were also determined in rat’s serum. Most organs functions were improved and approached nearly the negative control levels of S.G.O.T., S.G.P.T., S.G.O.T./S.G.P.T. ratio, s. albumin, s. total protein, s. globulin, s. total bilirubin, albumin/globulin ratio, s. uric acid and blood urea. Also, s. glucose was nearly returned the negative control group.