The aim of this research was to determine the prevalence of Cryptosporidium spp. in ostriches reared in the state of Rio de Janeiro. The diagnosis of oocysts of Cryptosporidium spp. in the feces of 77 ostriches was done by modified Ziehl-Neelsen technique. The occurrence was observed in 44.4% of the examined animals. However, in a property 100% of the ostriches shed oocysts in their feces. Oocysts was subspherical in shape with 6.33 +/- 1.27 (4.31-9.63) by 5.90 +/- 1.18 (4.07-9.42) mm and shape index of 1.07 +/- 0.05 (1.00-1.29). Was verified a high occurrence of oocysts elimination. In spite was observed a uniform distribution of the oocysts measurements in the regression line (R2 = 0.9438) accentuated difference was evidenced in the morphometry of the oocysts, that suggests that more of a species of Cryptosporidium are parasitizing these birds.