At the Institute of Pathology of Tübingen University 12 members of the staff (nine doctors, one secretary, one cleaner, and one autopsy assistant) fell ill with an influenza-like disease with high fever. In 11 instances there was positive serological evidence of Q-fever. The post-mortem room assistant was not tested serologically, but the disease followed a typical course. All those who fell ill had taken part in post-mortem examinations or a case demonstration at the Institute of Pathology. Seven more doctors fell ill at about the same time. They were working at two different clinic buildings, 1 km apart. They and one medical student had positive serology for Q-fever. No other cases of Q-fever were reported among clinic personnel. All doctors and very likely also a student who fell ill had taken part in the above mentioned case demonstration at the Pathology Institute, 19 days before the mean onset of the disease. No other possible sources of infection were found. In none of the 12 patients who underwent autopsy at the time was there clinical evidence of Q-fever; it was not possible to determine the source of infection retrospectively.