During 1994-1995, the etiological structure of children's diarrhea was monitored in outpatients at Mahosot Hospital, Vientiane, Lao PDR. Of the 191 children studied, 42% had stool specimens positive for enteropathogens; 22% had rotavirus, 21.5% enteropathogenic E. coli, 4.7% Shigella flexneri, 2.9% Campylobacter jejuni, 2.1% Shigella sonnei, and 0.5% each of Giardia intestinalis and Entamoeba histolytica. No Vibrio cholerae and Salmonella spp. was detected in this monitoring. In children under five years, rotaviruses were detected almost all round the year with a maximum prevalence in January in the dry season. Shigella species were highly detected in June to July in the rainy season.