An epidemic of Q fever in Berlin affected at least 80 patients (45 females, 35 males; age range 1-75 years). Sheep were identified as the focus of infection: they had been brought to a veterinary clinic because of nonspecific symptoms. The peak incidence of the infection was in April and May, 1992. Most of the patients were staff or students at the veterinary clinic. This is the most northern and, at the same time largest, Q fever epidemic recorded in Germany over the last 28 years. The complement fixation reaction (CFR) was not helpful diagnostically in the acute stage of the disease as it remained negative in the first 14 days (CFR < or = 1:5). Most of the patients had sudden fever to over 40 degrees C, severe headache and dry cough. Pulmonary infiltrates were seen in the chest radiograph of 8 of the 10 patients presented in this contribution. Auscultation was largely negative. Two patients had signs of hepatic involvement (GPT as high as 71 U/l). The drug of choice was doxycycline at a dosage of 200 mg twice daily for 14 days.