A retrospective study was undertaken in Crete, Greece, to investigate the epidemiologic, clinical, and therapeutic aspects of Q fever. Over a period of 5 years (1989-1993), 1,298 patients were examined and 98 cases were identified. Individuals who were aged 20-29 years and 30-39 years appeared to have an increased risk of infection. Contact with animals was found to be a major risk factor for acquisition of Q fever. The predominant clinical manifestations of the infection were fever (91.7% of patients) and respiratory disease (88.5%), whereas hepatitis was the dominant feature in only a minority (7.1%) of patients. Chest radiographs frequently revealed pulmonary interstitial changes (36.4% of patients) and alveolar changes (34.4%). Abnormal echocardiographic findings were also observed. There was no difference in the duration of fever whether the patient received therapy with tetracycline or erythromycin, a finding that may be explained by the delay in initiating tetracycline therapy.