The night visit record of an out-of-hours rota service of a large health centre which includes 10 group practices was examined. The mean annual night visiting rate for the health centre was 35.2 per 1000 patients, ranging from 25.8 to 43.5 between individual practices. The organization of medical care at night was the same for all the practices, and no major demographic differences between practices were identified. It is argued that the doctor-patient relationship may have an influence on differences in night visiting rates.