Hantavirus infection was confirmed by history, symptoms and biochemical changes, as well as immunofluorescence test in 29 patients (24 men, 5 women; mean age 36.9 +/- 11.5 years) with nontraumatic renal failure (ANF), retrospectively in 15 patients. Cardinal symptoms were acute onset (n = 29), fever (n = 27), pain in the flanks, abdomen or head (n = 27), reduced glomerular filtration rate (n = 29), proteinuria (n = 25) and thrombocytopenia (n = 16). Normal renal function was restored in all patients. Follow-up examination of 15 patients 6-7 years after the acute illness revealed normal blood pressure, normal serum creatinine, absent proteinuria and normal inulin clearance in all, thus confirming the favourable prognosis of the infection in Western Europe. Nonetheless, because Hantavirus infection is by no means rare, it should be included in the differential diagnosis of acute renal failure.