Two triales was carried to isolate mycoplasma from poultry with different ages from different localities (broiler and baldi breeds). Senun samples from the same birds were examined.Firstly we collect 154 swabs from nostriles, trachea, airsacs and lungs frExamination of the first 44 swabs for isolation and sera by S.P.Arevealed that, isolation and characterization of 6 strains of M.gallisepticum (13.6%) and 2 strains of Msynoviae (4.5%). Forteen senun samples contain antibodies for M.G. (31.8%) and 5 senun samples contain antibodies for M.S. (11.360/0). Most of samples Some samples proved positive in isolation not contain antibodies inserum by S.P .A. and vice versa,The other 110 swabs and senun samples were collected till the isolates reach to 35 strains kept as agar block at -20°C. When the viability test carried on these strains there was 24 strains found in active state and11 not viable. Characterization of the viable isolates using differentbiochemical and serological tests the strains were typed as follow.-9 M.gallisepticum (37.5%), 7 M. iners (29.1 %), 4 M.gallinarum(16.66%),2 M.synoviae (8.3%) and 2 un typed. Sensitivity test was carried on different mycoplasma isolates wherethese diseases.Our study was conducted on two localities atDakahlia Govemorate including Shoha and Aga breeding farms, a total of one handred and twenty diseased and forty apparently normal calves housed in the fore mentioned areas were examined.Representive samples of whole blood, serum and nasal swabs aswell as lung specimens were obtained and investigated according tothe clinical signs. Thus haematological, biochemical, bacteriological, post-mortum and histopathological studies had been carried on the collected samples as well as chemotherapeutic trials among pneumonic animals in comparison with the auto-control groupThe clinical picture of diseased calves included typical signs of bronchitis and bronchopneumonia which was described in details and discussed.The cytological studies of whole blood samples involved red and white blood cells counts, differential leucocytic count, haemoglobin content, as well as blood gases and acid-base balance of both diseased and apparently healthy calves.