All previous studies of intestinal parasites in Southeast Asian refugees have included immigrants with and without symptoms. In order to determine the prevalence of intestinal parasites in asymptomatic Southeast Asians, 226 adult refugees were studied who had no symptoms or signs suggestive of intestinal parasitism and who submitted one to three stools for examination. Fifty-four percent of these asymptomatic adults were infected with one or more potential pathogens, 22 percent with Ascaris, 20 percent with hookworm, 11 percent with Opisthorchis sp, 7 percent with Trichuris, 5 percent with Strongyloides, 5 percent with Giardia, and 2 percent with Entamoeba histolytica. Laotians and Cambodians, persons who stayed in Thai refugees camps, and patients with anemia or eosinophilia were more likely than other refugees to harbor pathogenic parasites. Nonetheless, refugees without these characteristics were often infected, and no single characteristic excluded any refugee from a high probability of being parasitized. There is a high prevalence of potentially pathogenic parasites in asymptomatic adult Southeast Asians, similar to that reported in refugees unselected for the presence or absence of symptoms.