To evaluate the prevalence of intestinal parasitic infections and to investigate the possible associations of clinical status and laboratory findings with the different parasites found in stool samples. Each patient was provided with one standard fecal collection vial containing 10% formalin for detecting ova, larvae, and cysts. To detect Cryptosporidium parvum and Isospora belli, the acid-fast Kinyoun stain and fluorescent auramine-rhodamine stain were used. A total of 200 patients with acquired immunodeficiency syndrome participated in this study; 40% were infected with at least one pathogenic species. The total prevalence of parasites was 16% for Giardia lamblia, 13% for Entamoeba coli, 7% for Cryptosporidium parvum, 3.5% for Endolimax nana, 2.5% for Ascaris lumbricoides, 2.5% for Strongyloides stercoralis, 2% for Isospora belli, and 0.5% for Blastocystis hominis. Results showed that diarrhea was significantly associated with cryptosporidiosis, giardiasis, and isosporiasis. However, no association was observed between the CD4+ cell counts and the manifestation of any particular parasite. The data support the value of standard fecal examinations in human immunodeficiency virus-infected patients, even in the absence of diarrhea, since these examinations easily can be performed, with low costs, and frequently disclose treatable conditions.