Objectives: Controversy exists regarding the benefit of extended lymphadenectomy at radical prostatectomy for prostate cancer. We sought to determine whether more extended lymphadenectomy, along with radical prostatectomy, resulted in a decreased risk of prostate cancer-specific death at 10 years. Methods: Data on all patients undergoing radical prostatectomy (with or without lymphadenectomy) for prostate cancer obtained from the Surveillance, Epidemiology, and End Results Program (1988 to 1991) were examined. All surviving patients had a minimal follow-up of 10 years. Multivariate Cox proportional hazards analysis was used to determine the independent effect of lymphadenectomy on the risk of prostate cancer-specific death. Results: Patients undergoing excision of at least 4 lymph nodes (node-positive and node-negative patients) or more than 10 nodes (only node-negative patients) had a lower risk of prostate cancer-specific death at 10 years than did those who did not undergo lymphadenectomy. The removal of a greater number of nodes was associated with a greater likelihood of the presence of positive nodes. The presence of more than one positive node was associated with a greater risk of prostate cancer-related death. Conclusions: Performing more extensive pelvic lymphadenectomy in patients undergoing radical prostatectomy could improve the accuracy of staging and reduce the risk of prostate cancer-specific death in the long term.