Four hundreds samples of lung, liver, muscle and synovia were collected from 100 slaughtered Friesian and buffaloe calves (50 of each) examined for the prevalence of mycoplasma infection. The PH of examined samples was measured. 35 isolates of mycoplasma were isoalted and identified as M. bovigenitalium (16), M. arginini (11), M. bovis (7) and M. alkalescens (once). Most of isolates were recovered from Friesian calves, while buffaloes seems to be more resistant. The average PH values were 5.66, 6.73, 6.33, 7.68 in examined buffaloes muscle, lung, liver and synovia samples and 5.66, 6.61, 6.29, 7.67 in Friesian calves samples respectively. Slight elevation of PH value was recorded in mycoplasma positive  samples. The hygienic significanceof isoalted microorganisms was discussed.