OBJECTIVE: To determine whether specific viruses are associated with HIV infection in Tanzanian children with chronic diarrhea. DESIGN: Cross-sectional survey. SETTING: Major national teaching hospital in Dar es Salaam, Tanzania. PATIENTS: Consecutively admitted, human immunodeficiency virus (HIV)-infected and HIV-uninfected children with chronic diarrhea, and controls without diarrhea, aged 15 months to 5 years. MAIN OUTCOME MEASURE: Enteric viruses identified by electron microscopy (EM) of fecal specimens. RESULTS: Small round structured viruses (SRSV) were more frequent in HIV-infected than HIV-uninfected children with chronic diarrhea (4 of 21 vs 1 of 32, prevalence ratio = 6.09, 90% confidence limits 1.03, 36.14). Rotavirus and coronavirus-like particles (CVLP) were not associated with HIV infection. CONCLUSION: SRSV may be associated with HIV infection in Tanzanian children with chronic diarrhea. Larger, confirmatory studies are needed.