BACKGROUND: Many of the characteristics of patients with familial epithelial ovarian cancer (EOC) are not yet well defined. This report describes some of the characteristics of patients with EOC in particular response rates to chemotherapy and 5-year survival, and compares them with matched controls with sporadic EOC. PATIENTS AND METHODS: There were 28 cases of familial epithelial ovarian cancer (EOC) presenting to the Royal Marsden Hospital from January 1983 to September 1993. The incidence of familial EOC over this time period was 2.2% (28/1268). For each case of familial EOC, 3 controls were selected and matched for age, FIGO stage, volume of residual disease after initial surgery and type of chemotherapy; the matched controls were compared to the familial EOC cases for differences in histological subtype, response to chemotherapy and 5-year survival. There was a statistically significant difference in histological subtype, 83% of patients with familial EOC had serous cystadenocarcinoma compared to 49% in the matched control group (p = 0.0025) providing evidence that familial EOC has a genetic basis. However there were no differences in median age or FIGO stage between patients with familial EOC and the sporadic cases and no difference in overall response to chemotherapy or 5-year survival. CONCLUSIONS: Our results imply that familial and sporadic EOC are biologically very similar and therefore molecular studies on the pathogenesis of and cellular mechanisms involved in EOC may have an important impact on therapeutic strategies for the much commoner sporadic form of the disease. In addition, our data suggest that all patients should be closely questioned with regard to family history not just those who present at a young age.