Strongyloides stercoralis (SS) is an intestinal nematode which infects a large proportion of tropical and subtropical populations. The endemic areas are southeast Asia, South America and sub-Saharan Africa. Infection is acquired when the worms penetrate the skin, pass via the blood stream to the lungs, ascend the respiratory tract, are swallowed and grow into adult worms in the mucosa of the small intestine. The eggs laid by the female release larvae which pass down the lumen and reach the soil via the feces. While passing down the intestinal tract, a few of the rhabditiform larvae may be transformed into infective filariform larvae which can penetrate the distal intestinal and anal mucosa, returning to the blood stream. This "autoinfection" cycle is unique to SS, and explains why the infection can be perpetuated without further exposure to exogenous, infective larvae and can persist decades after departure from endemic areas. A substantial proportion of those affected are asymptomatic, but overwhelming infection may occur in immunosuppressed patients. This "hyperinfection" state is characterized by severe gastrointestinal and respiratory tract involvement, along with skin rash, Gram-negative bacteremia and cerebral signs. While frequently fatal, it is curable when diagnosed and treated promptly. We present a 79-year-old woman with idiopathic polymyositis, who was immunosuppressed by prolonged corticosteroid treatment. Her illness was complicated by SS hyperinfection. Diagnosis was made from stool and bronchial smears. Treatment with thiabendazole was started early and within a week there was complete cure. This is the fourth reported case of SS hyperinfection treated in Israel.