PROPOSE: THE TUMOR CELL PROLIFERATION HAS BEEN SUGGESTED AS A PROGNOSTIC PARAMETER IN VARIOUS STUDIES. THIS STUDY INVESTIGATED THE PROGNOSTIC VALUES OF TUMOR CELL PROLIFERATION MEASURED BY PROLIFERATIVE CELL NUCLEAR ANTIGEN (PCNA) AND KI-67, AND COMPARED THEM BETWEEN A METASTATIC GROUP (MG) VS A LOCALIZED GROUP (LG) WITH LOWER RISK OF PROGRESSION. METHODS & MATERIALS: PATIENTS OF METASTATIC GROUP (N=22) WHO HAD SEMINAL VESICLE INVASION AND/OR LYMPH NODE METASTASIS, AND PATIENTS OF LOCALIZED GROUP (N=18) WHO HAD LOCALIZED CANCER WERE CATEGORIZED. PATIENTS OF LG WERE SELECTED RANDOMLY BY THE CRITERIA OF GLEASON SUM SCORE (GSS), AGE AND PREOPERATIVE PSA. REPRESENTATIVE 2 OR 3 TISSUE BLOCKS FOR EACH PRIMARY TUMOR TISSUES WERE SELECTED AND NEW SLIDES WERE PREPARED. IN 10 MICROSCOPIC FIELDS MORE THAN 1000 CELLS WERE COUNTED AT 40X HIGH POWER MICROSCOPIC FIELD BY TWO OBSERVERS AND THE PERCENTAGE OF KI-67+AND PCNA+CELLS WERE ACCEPTED AS KI-67 LABELLING INDEX (KI-67 LI) AND PCNA LABELLING INDEX (PCNA LI), RESPECTIVELY. KI-67 LI AND PCNA LI WERE COMPARED BETWEEN LG AND MG, AND ALSO BETWEEN DIFFERENT PATIENT GROUPS IN RESPECT TO PROGRESSION. RELATIVE IMPORTANCE OF THE TWO LIS FOR PATHOLOGIC STAGE, PROGRESSION AND PSA FREE SURVIVAL WAS ALSO EVALUATED. FINALLY, USING MULTIVARIANT ANALYSIS, PROGNOSTIC VALUES OF THESE LIS WERE ANALYZED. RESULTS: LIS OF KI-67 AND PCNA REVEALED SIGNIFICANT ASSOCIATION BETWEEN GSS, PATHOLOGIC TUMOR STAGE, PROGRESSION AND PSA FREE SURVIVAL, RESPECTIVELY. PROGRESSION IN THE MG (15.22) WAS SIGNIFICANTLY HIGHER THAN THE LG (2.18). BOTH KI-67 LI AND PCNA LI SHOWED MARKED DIFFERENCE BETWEEN LG AND MG AND IN RESPECT TO PROGRESSION. IN MULTIVARIATE ANALYSIS, INDEPENDENT FACTORS FOR PROGRESSION WERE TUMOR STAGE, SURGICAL MARGIN AND PCNA LI WHEN GSS, ORGAN CONFINEMENT, POSITIVE SURGICAL MARGIN AND INVOLVEMENT OF PROSTATE CAPSULE, SEMINAL VESICLE INVASION, LYMPH NODE METASTASIS AND PCNA LI OR KI-67 LI WERE INCLUDED. DISCUSSION & CONCLUSION: TUMOR CELL PROLIFERATION DETERMINED BY PCNA OR KI-67 SIGNIFICANTLY CORRELATED WITH PROGRESSION AND PCNA LI WAS FOUND TO BE AN INDEPENDENT PROGNOSTIC FACTOR BY MULTIVARIATE ANALYSIS.