In Tula Province [correction of Region], the affliction of its population with cryptosporidiosis has been first estimated at 0.2%. Cryptosporidium infection has been recorded in 0.5% of cases among patients with acute gastrointestinal diseases, in 0.6% among cattle-breeders, and in 7.2% among agricultural animal (pigs). Low-immunity children under 4 years mainly suffer. Cryptosporidiosis ran as a moderate monoinfection and in one case it was severe. Two cases of cryptosporidiosis were simultaneously detected in the familial focus. The source of infection could not be established.