ABSTRACT
Microsporidia are protozoan parasites responsible for significant gastrointestinal disease in patients infected with the human inmunodeficiency virus. We reporte the clinical features of three patients with chronic diarrhea and intestinal microsporidiosis caused by Enterocytozoon bieneusi. The average value for CD4 in these patients was ó 50 cells/mm3. The spores were detected in smears from stool samples and duodenal aspirates stained with trichrome blue in all patiens. Light microscopy of semithin plastic sections revealed parasites and spores in the enterocytes and were associated with villous atrophy (2 out of 3). Thin section-electron microscopy showed a variety of developmental stages of the microsporidio. Patients treated with Albendazole had an unsatisfactory clinical response to therapy. Enterocytozzon bieneusi infection may be an important cause of diarrhea in patiens with AIDS in our country.