Strongyloidiasis is usually a benign illness confined to the gastrointestinal tract. However, dissemination (hyperinfection syndrome) may occur, particularly in patients with impaired cell-mediated immunity. The diagnosis of hyperinfection syndrome is often made postmortem, and mortality is high, even when the disease is recognized during life. Central nervous system involvement with Strongyloides stercoralis has previously been recognized in only a few cases at postmortem examination, and in one case antemortem. We describe a patient with disseminated strongyloidiasis in whom central nervous system involvement was diagnosed antemortem. This patient developed multiple bacterial and fungal systemic and central nervous system infections as a complication of disseminated strongyloidiasis. The natural history of the disease in man, factors predisposing to dissemination, immunologic aspects of helminthic infection, treatment modalities are discussed.