The genesis of ovarian granulosa cell tumours (GCT) has been linked to high gonadotrophin levels, and therefore also to the use of ovulation inducers and combined contraceptive pills (OC). We analysed the occurrence of GCT in the whole of Finland in 1965-1994, the period when ovulation inducers and OC became available. All women with GCT were traced from the Finnish Cancer Registry. The numbers of courses of clomiphene citrate and gonadotrophin (human menopausal gonadotrophin: HMG) and number of courses of OC used in Finland during the same period were calculated from sales statistics on these agents. In 1965-1994, 590 patients contracted GCT. The incidence of GCT declined by nearly 40% from 0.74/100000 in 1965-1969 to 0.47/100000 in 1985-1994, a fall occurring at the same time that the use of clomiphene citrate increased 13-fold, that of HMG 200-fold and that of OC 5-fold. Our nationwide data on the incidence of GCT falling concomitantly with increasing use of ovulation inducers can be seen as one piece of evidence that ovulation inducers are unlikely to cause GCT.