OBJECTIVE To describe the main features of severe strongyloidiasis in corticosteroid-treated patients METHODS We report on 3 cases of corticosteroid-treated patients with severe strongyloidiasis and review cases of severe strongyloidiasis in corticosteroid-treated patients reported in the literature. RESULTS One hundred and fifty-one cases of severe strongyloidiasis complicated a therapy with corticosteroids were evaluated. The mean age of the patients was 48+/-17 years and 71% were men. Corticosteroids were given for hematological malignancies in 34 (23%), systemic lupus erythematosus or vasculitis in 27 (18%), and nephropathy or renal transplantation in 32 (21%). At time of infection, the mean daily dosage of prednisone-equivalent was 52+/-42 mg (median: 40 mg) and 84% of patients had received a cumulative dosage of prednisone-equivalent higher than 1000 mg. The total duration of treatment ranged from 4 days to 20 years (6 months or less: 69%). Non-specific gastro-intestinal symptoms were reported in 91% of these patients associated or not with pulmonary complaints. Low-grade fever was present in 54% of patients. Fifty-nine patients (39%) experienced severe bacterial or yeast infection during the course of severe strongyloidiasis. Peripheral eosinophilia was detected at presentation in 32% of patients. Strongyloidiasis was usually confirmed by repeated stool examinations. Thiabendazole was the treatment the more widely used. Eighty-nine patients (59%) deceased during the course of the disease. CONCLUSIONS Severe strongyloidiasis is a risk in every corticosteroid-treated patient who has traveled to a soil-infested country, even if the contact was 30 years prior. This diagnosis should be suspected in patients who either experience unusual gastro-intestinal or pulmonary symptoms or suffer from unexplained Gram-negative bacilli sepsis.