We report here three cases of severe strongyloidiasis in normal and immunocompromised hosts. The first was a patient with a normal immune system who presented with acute severe abdominal pain. The second and third patients were immunocompromised due to steroid and chemotherapy treatment of underlying diseases. Both presented with obstructive symptoms. In all three cases, Strongyloides stercoralis larvae were detected in stool concentration samples, and in biopsied specimens from the duodenum in the first and second cases.