The aim of the study was to determine the prevalence of Cryptosporidium and Eimeria in thoroughbred foals from Lima. During the months from August through December 1998, a total of369 fecal samples were collected at severa) breeding centers from suckling foals aged O to ?2 weeks. Direct fresh smears were fixed with methanol and processed using modified Zielh Neelsen stain for cryptosporidia diagnosis. For Eimeria, the samples were concentrated using Formalin-ether sedimentation and examined microscopically. Cryptosporidium prevalence was 48 ± 5% (176/369) with a corrected value of 55 ± 5%, and statistically significant differences were found among animals belonging to different age groups (P< 0.001). Six out ofthe 369 samples examined for Eimeria were positive (2 ± 1 %). None ofthe Cryptosporidium or Eimeria positive foals had diarrhea, and the two foals with diarrhea tested negative to both protozoa.