Clinical and epidemiological data on 16 patients with HFRS admitted to the University Hospital of Infectious Diseases in Zagreb during the past 10 years (1977-1986) are reported. In 13 of them, the diagnosis was confirmed serologically by indirect fluorescent method. All but two were men between 20 and 45 years of age (80% of patients). The disease appeared sporadically only. According to the domicile, way of living and working all the patients but three mentioned the contact with rodents in the fields or in other places (mill, storehouse). Three patients live in Zagreb and there was no possibility to get infected out of the town. The disease had moderate course, more rarely severe course when shock and acute renal failure developed. General symptoms with fever and algias dominated (febrile stage). Some of the patients had ophthalmic disturbances. Patients with a pronounced gastroenteritis developed shock the most frequently. In some of the patients back and abdominal pains followed by obstipation appeared. HFRS was incriminated disease because of febrile stage followed by the acute renal failure, oliguria, azotemia, polyuria and low urine osmolity. One female patient with active rheumatoid arthritis died after two-week staying in hospital due to irreversible shock followed by cardiopulmonary and renal failure.