Cryptosporidiosis is an emerging parasitosis due to an intracellular protozoan, Cryptosporidium sp. The objective of our work was to determine the prevalence of Cryptosporidium sp in subjects with diarrhea it is a prospective descriptive, cross-sectional and analytical study that was conducted during a period of 05 months from 01/10/2016 to 28/02/2017. It focused on stool samples sent to the laboratory of parasitology of the CHU Constantine. Each stool was concentrated and stained (modified Ziehl Nelseen) for Cryptosporidium sp. oocysts. Among the 80 stool samples examined during the period...