Strongyloides stercoralis usually causes chronic asymptomatic infection in humans. However, in patients with AIDS, malignancy, and individuals receiving corticosteroids, disseminated infection can develop, associated with an extremely high mortality rate and frequent treatment failure with thiabendazole. Recently, ivermectin was found to be very effective in such patients. The authors report a case of strongyloidiasis in a patient with hypogammaglobulinemia in which ivermectin failed to clear Strongyloides larvae from stool, despite repeated courses of treatment throughout 14 months.