OBJECTIVE To investigate the relationship between the clinicopathological stage and serum prostate specific antigen (PSA) concentration and PSA density (PSAD) in patients with prostate cancer.METHODS The clinicopathological stage was determined on the basis of a pathological examination and clinical data in 65 prostate cancer patients treated by radical prostatectomy. PSA and PSAD were measured before the operation. The Spearman rank correlation was applied to evaluate the relationship between the clinicopathological stage, serum PSA concentration and PSAD.RESULTS Patients with higher PSA and PSAD were significantly more likely to have higher clinical stages, a higher Gleason score, positive surgical margins, capsular penetration, and seminal vesicle invasion (each P＜0.05).But there was no significant association between PSA and lymph node metastasis (P=0.053). The levels of serum PSA concentration and PSAD were significantly correlated with the clinical stage (P＜0.05) in the prostate cancer patients.CONCLUSION The level of both PSA and PSAD were significantly correlated with the clinical stage (P＜0.05) in the prostate cancer patients. But PSAD may be a more powerful predictor of clinical stage and prognosis than PSA.