Objective: to elaborate an algorithm suitable to discriminate clinical groups of prostate cancer (PC) patients and to compare its diagnostic value with prostate-specific antigen (PSA)-associated parameters. Subjects and methods. The investigation enrolled 332 primary patients with a verified diagnosis of PC and PSA levels of below 30 ng/ml who had undergone radical prostatectomy at the P.A. Herzen Moscow Oncology Research Institute. The serum levels of total PSA (ng/mg), free PSA (ng/mg), and [-2]proPSA (pg/ml) were estimated by chemiluminescent PSA assays (Access Hybritech p2PSA assay) and used to calculate %free PSA, %[-2]proPSA, prostate health index (PHI), and laboratory clinical staging index (LCSI), a new multiparameter indicator. The findings were compared with the stage of a tumor process (Tumor, Node, and Metastasis (TNM) staging system) and Gleason cancer grade in accordance with a postoperative histological report. Results. Statistical differences were established to be achieved in each of these parameters for pT2c versus pT3a and for [-2]proPSA in addition for pT3a versus pT3b. There was a significant difference in total PSA, PHI, and LSCI between localized indolent and aggressive PC; in all the parameters between localized and locally advanced PC, and in [-2]proPSA between locally advanced PC and PC with regional metastases. Statistically significant differences were achieved in total PSA, %[-2]proPSA, PHI, and LSCI between the groups of patients with Gleason scores 5-6 and 7 (3+4), as well as in [-2]proPSA, PHI, and LSCI between the groups of those with Gleason scores 7 (3+4) and 7 (4+3). Conclusion. General decision rules were formulated for LSCI, which permit one to distinguish the clinical stages of the disease in at least some patients prior to surgery.