Long-term trends in the incidence, prognosis, and mortality of patients with ovarian cancer and borderline tumours in Norway were examined based on data from the population-based Cancer Registry of Norway. The incidence of ovarian cancer rose continuously from the mid-1950s to the mid-1980s. There was also an increasing trend in the incidence of borderline tumours from the early 1970s to the early 1990s. The prognosis for patients with ovarian cancer has improved since the 1950s. In 1989-93 the five-year relative survival rate was 37%. The prognosis for patients with borderline tumours was very favourable, with a five-year relative survival rate of 93% (1970-93). The mortality from ovarian cancer has been almost constant since the 1960s.