A total of 1042 patients diagnosed with uterine sarcoma were reported to The Cancer Registry of Norway from 1956 to 1992. In the present study long-term trends in incidence, survival and mortality were analysed. To evaluate the effect of the introduction of chemotherapy in the treatment of this disease, special attention was paid to the time periods 1971-1975 and 1983-1987. The reporting system is based on pathology reports, clinical records and death certificates. Histological type, diagnostic period, clinical stage and age were included in the study. The analysis of survival was based on 5-year relative survival. Both the incidence and mortality rate of uterine sarcomas in Norway doubled in the time period 1956-1992, mainly due to an increase of carcinosarcomas. The overall annual incidence rate in 1987-1992 was 1.7 per 100000 females in the population per year, accounting for 9.7% of all uterine corpus malignancies. In 1990-1992, 26% of the mortality due to uterine corpus malignancies was caused by sarcoma. No change in 5-year survival was seen after the introduction of chemotherapy in the treatment of the disease (P = 0.35). Stage (P < 0.001) and age (P < 0.001) were both important prognostic factors. Patients with an endometrial stromal sarcoma (P < 0.001) had a more favourable prognosis than those with other histological types.