The protozoan Cryptosporidium an animal pathogen has recently ben found to be a common cause of gastroenteritis in immuno-competent calves (O'DONOGHUE , 1985). During one year study on four hundred and eighty Friesian calves (below two years old) at El-Diabat farm for milk and meat production in Sohag Governorate. Cryptosporidium oocysts were detected in the faecal samples of 163(33.96%).- out of 480 cases by microscopical examination of modified Ziehl-Neelsen stained fixed smears. Cryptosporidium was the sole pathogen detected in 95(19.79%) of the positive cases, in the other hand 68 cases (14.17%) mixed infection were observed with one or more other intestinal parasites. The highest incidence of infection was recorded in the group one day to one month old. As regards the sex, no specific difference was discernible. The highest infection with the parasite was during the summer and autumn seasons. Most of the calves deficate watery diarrhoea with a mild to moderate degree of dehydration, the diarrhoea was noticed for less than seven days.