During the five-year period 1982-86, 1,087 clinical drug trials were notified to the Norwegian Medicines Control Authority. There was in this period a slight decline in the annual number of notifications, whereas the number of patients/volunteer subjects in clinical trials rose. During the five-year period, every fifth professionally active physician in Norway notified at least one clinical trial to the Authority. Less than 10% of the trials notified did not involve participation by manufacturers. The trials covered a large number of substances. Most trials concerned drugs in the cardiovascular (c) and central nervous system (N) therapeutic groups. The frequency of reports on completed trials is low, and there are signs that some obligatory notifications of clinical trials are not sent to the Authority.