Aim: This study was carried out to determine the prevalence of Cryptosporidium sp. in calves with diarrhea in University of Selcuk, Department of Parasitology between 2005 and 2009.

Materials and Methods: Faecal samples were collected from 1-35 days old 368 calves. Faecal samples were stained with Modified Ziehl-Neelsen staining technique, they were examined under light microscope for the presence of Cryptosporidium sp. oocysts.

Results: Out of 368 faecal samples, 145 (39.4%) were found to be infected with Cryptosporidium sp. oocysts. Cryptosporidium sp. oocysts were seen in 1-10 days age calves at the highest level (46%) and 11-20 days age at the lowestlevel (31%).

Conclusion: C. parvum should be considered in the treatment of diarrhea in neonatal calves.