From 1973 to 1983 nine cases of Brucella melitensis infection were hospitalised at the Centre hospitalier universitaire vaudois (CHUV), Lausanne. In each case, the infection was acquired in a Mediterranean country (4 cases in Italy, 2 in Spain, 2 in Portugal and 1 in Greece). In 6 of the cases the disease was acquired by ingestion of dairy products and in 2 cases by direct animal contact. Despite classical initial symptomatology (fever, rigors, weakness), the time from first symptoms to diagnosis varied between 10 days and 5 months. This delay probably explains why 6 of 9 patients were admitted because of septic complications: orchi-epididymitis, arthritis, meningitis and endocarditis. With prolonged antibiotherapy, the evolution was favourable in all cases. The patient who presented with endocarditis required emergency aortic valve replacement. Culture of the valve showed the presence of 10(9) B. melitensis/g of tissue. Cure was achieved by the administration of streptomycin and tetracycline for 6 weeks, followed by cotrimoxazole for one year. These cases show that the diagnosis of Brucella infection is becoming rare in Switzerland. It is often not suspected, and prompt diagnosis is delayed until further complications occur. Serology and blood cultures should be done in every patient presenting with fever after a stay in endemic countries.