In the present work there is a literature review of many important biological activities of benzimidazoles, 1,3,4 thiadiazole, 1,2,4 triazole, 1,3,4 oxadiazole, sugar hydrazones and peptide derivatives and different methods for their preparation. The mono peptide derivatives VIa-e, VIIa-e, IXa-d&f, Xa-d&f, XIa-d, XIIa-d and XIIIa-d were synthesized by the condensation of 2- chloroacetamido aminoacid esters IIIa-e with either aliphatic or aromatic benzimidazole derivatives (Scheme1) and (Scheme2), respectively. 2- Chloroacetamido aminoacid esters were prepared by stirring the hydrochloride of amino acid esters Ia-e with triethylamine and chloroacetyl chlorid II. Hydrazinolysis of VIa&c and VIIa leaded to acetohydrazide derivatives XIVa&b and XVa. The acetohydrazide derivatives XIVa and XVa were used to prepare the dipeptide derivatives XVIa&b and XVIIa&b by treating acetohydrazide derivatives XIVa and XVa with HCl/ NaNO2 and acetic acid to prepare azide intermediate that was reacted with free aminoacid ester a or b (Scheme 3). Also, acetohydrazide derivatives XIVa&b and XVa were refluxed with phenylisothiocyanate to obtain the thiosemicarbazide derivatives XVIIIa&b and XIXa. Cyclization of these thiosemicarbazide derivatives using conc H2SO4 gave 1,3,4 thiadiazole derivatives XXa&b and XXIa, while with KI/I2 at room temperature gave 1,3,4 oxadiazoles XXIVa&b and XXVa. Also, 1,2,4 triazoles XXIIa&b and XXIIIa were obtained by condensation of thiosemicarbazide XXIIa&b and XXIIIa with pipridine (Scheme 4). On the other hand, ethyl P- amino benzoate (XXVI) was stirred at room temprature with chloroacetyl chloride II to give ethyl 4-(2-chloroacetamido) benzoate (XXVII). Moreover, the condensation of XXVII with benzimidazole Va yield ethyl 4-(2-(1 H benzimidazole acetamido) benzoate (XXVIII). The hydrazinolysis of XXVIII gave acetohydrazide XXIX that was refluxed with phenyl isothiocyanate to give XXX. Cyclization of thiosemicarbazide derivative XXX with either conc H2SO4 or KI/I2 gave 1,3,4 thiadiazole derivative XXXI and 1,3,4 oxadiazole derivative XXXII respectively (Scheme 5). Also, condensation of the acetohydrazide derivative XXIX with aromatic aldehyde derivatives XXXIIIa-c and aldoses XXXVa-d yielded hydrazone derivatives XXXIVa-c (Scheme 6) and sugar hydrazone derivatives XXXVIa-d (Scheme 7). The new compounds were evaluated for their antimicrobial activity against Gram positive bacteria (Bacillus subtilis), Grame negative bacteria ( Pseudomonus aeorgionosa and Echercia coli) and antifungal activity against (Asperigillus fumigatus and Candida albicans) also, some compounds were evaluated against Gram positive bacteria (Streptococcus pneumonia). Compounds VIc, Xa, Xb, XIa, XIIc, XIIIa, XIVa, XIVb, XVIIIa, XXIVb exhibited comparable activity to the stander drug (Ciprofloxacine) in term of zone of inhibition against (Echercia coli). Also, the tested compounds did not show activity against Grame negative bacteria except compound IXf. Minimum inhibitory concentration (MIC) showed that compounds VIc, Xa, XIVb, XXIb, XXIIb and XXIIIa have the same (MIC) as stander drug (Ampicillin) against ( Bacillus subtilis) which is 0.49µg/ml. Also, compounds VIc, Xa, XIa, Xb, XIIc, XIIIa, XXIIIa and XIVb have the same (MIC) as stander drug (Ciprofloxacine) against (Echercia coli) which is 0.98 µg/ml. The X-ray structure of compounds VIa, XIIc and XIIIc were obtained. The X- ray structure of compound XIIc and DFT- geometrical optimization were used to explain the 13 C NMR splitting of carbon signal of methylene group that is attached benzimidazole ring in 2 or 2,4 difluorobenzimidazole XIa-d and XII a-d. Also, The DFT- geometrical optimization was used to explain the 1H NMR splitting of proton signal (SCNHPh) in compound XXa that was due to two isomers with a small difference in energy. Moreover, docking study was done for some compounds to explain their activity.