Analgesic use may reduce ovarian cancer risk, possibly through antiinflammatory or antigonadotropic effects. The authors conducted a population-based, case-control study in Washington State that included 812 women aged 35-74 years who were diagnosed with epithelial ovarian cancer between 2002 and 2005 and 1,313 controls. Use of analgesics, excluding use within the previous year, was assessed via in-person interviews. Logistic regression was used to calculate odds ratios and 95% confidence intervals. Overall, acetaminophen and aspirin were associated with weakly increased risks of ovarian cancer. These associations were stronger after more than 10 years of use (acetaminophen: odds ratio (OR) = 1.8, 95% confidence interval (CI): 1.3, 2.6; aspirin: OR = 1.6, 95% CI: 1.1, 2.2) and were present for indications of headache, menstrual pain, and other pain/injury. Reduced risk was observed among aspirin users who began regular use within the previous 5 years (OR = 0.6, 95% CI: 0.4, 1.0) or used this drug for prevention of heart disease (OR = 0.7, 95% CI: 0.5, 1.0). These results, in the context of prior findings, do not provide compelling evidence of a true increase in risk of ovarian cancer among women who use these drugs. However, they add to the weight of evidence that, in the aggregate, provides little support for the use of analgesic drugs as chemoprevention for this disease.