To investigate the clinical and pathologic characteristics of prostate cancer in Korean men to determine how ethnic differences affect clinical outcome.The clinical and pathologic data of 604 Korean men who underwent radical prostatectomy from 1994 to 2003 were reviewed. Biochemical failure was defined as a prostate-specific antigen (PSA) level of 0.2 ng/mL or greater on two consecutive occasions after having achieved an undetectable PSA level. Patient distribution with respect to the clinical and pathologic parameters and biochemical failure rates were compared with those of contemporary Western series.The mean preoperative PSA level was 9.9 ng/mL (range 0.4 to 38.8) and the median biopsy Gleason score was 7. The Gleason score was 7 in 186 patients (30.8%) and greater than 7 in 169 (28.0%). Gleason scores stratified with respect to clinical stage and PSA range revealed the proportion of patients with high Gleason scores (7 or greater) to be more than 50% of each subgroup throughout the clinical stages and PSA ranges. At a median follow-up of 57.9 months (range 22 to 131), biochemical failure occurred in 24.2% of all patients and in 14.3% of those with an initial serum PSA level of 10.0 ng/mL or lower. On multivariate Cox regression analysis, the Gleason score showed the strongest statistical significance for biochemical failure (P = 0.001, hazard ratio 1.376, 95% confidence interval 1.056 to 1.792) for patients with a serum PSA level of 10.0 ng/mL or lower.A significant proportion of prostate cancers arising in Korean men exhibit poor differentiation, regardless of the initial serum PSA level or clinical stage at presentation, and adversely affect prognosis, causing a greater rate of PSA failure.