This pilot study examined the relationships of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) with prostate cancer. Ninety-nine controls were frequency matched by age in 5-year increments to 58 prostate cancer patients. Thirty PCBs and 18 OCPs were measured in serum by gas chromatography. Multiple logistic regression was used to assess the magnitude of association. Seven organochlorines, dieldrin, p,p'-DDE, trans-nonachlor, oxychlordane, heptachlor epoxide, and PCBs 153 and 180 were detected in at least 20% of all study participants. Adjusting for age, body mass index, and a history of prostatitis, oxychlordane and PCB 180 were associated with an increased risk of prostate cancer. This study suggests that long-term, low-dose exposure to specific OCPs and PCBs in the general population may contribute to an increased risk of prostate cancer and supports further investigation in this area.