This case-control study evaluated the risk of epithelial ovarian cancer associated with genital exposure to various forms of powder application. Cases included all women aged 20-79 years in three counties of western Washington who were diagnosed with borderline or invasive ovarian cancer from 1986 through 1988; 64.3% of eligible cases were interviewed. A sample of similarly aged women who lived in these counties, identified by random digit dialing, served as controls. The overall response among control women was 68.0%. Information on powder application and other potential risk factors was ascertained during the in-person interview. Overall, ovarian cancer cases (n = 313) were more likely than controls (n = 422) to ever have used powder (age-adjusted relative risk (RR) = 1.5, 95% confidence interval (CI) 1.1-2.0). After adjustment for age and other methods of genital powder application (none vs. any), an elevated relative risk of ovarian cancer was noted only for women with a history of perineal dusting (RR = 1.6, 95% CI 1.1-2.3) or use of genital deodorant spray (RR = 1.9, 95% CI 1.1-3.1). These results offer support for the hypothesis, raised by prior epidemiologic studies, that powder exposure from perineal dusting contributes to the development of ovarian cancer, and they suggest that use of genital deodorant sprays may do so as well. Limitations of the present study include the fairly low proportion of eligible women who participated and the potential differential recall of powder usage.