AIM: We evaluated the influence of ratio between free-to-total prostate specific antigen (F/T PSA) and prostate specific antigen density (PSAD)-(F/T)/PSAD on reduction of unnecessary prostate biopsies in grey zone (prostate specific antigen (psa) value 4.0-10.0 ng/ml). METHODS: The study included 108 patients. For all patients serum total PSA (T PSA), free PSA (F PSA), F/T PSA and PSAD were analyzed. The group was divided due to the prostate volume into: entire group (regardless the prostate VOL-Group 1) and group with prostate VOL<40 (Group 2). RESULTS: Seventy five patients were diagnosed with benign prostatic hyperplasia (BPH) and 33 with prostate cancer (CaP). F/T PSA and (F/T)/PSAD showed significantly lower values in patients with CaP versus those with BPH, while PSAD had significantly higher values. For the cutoff values of 1.12 for (F/T)/PSAD, we found sensitivity to be 67% and specificity 60%, and the (AUC) 0.701. For patients with VOL<40, statistical significance remained with AUC of 0.732 (p=0.003), cutoff was 0.82, and with sensitivity 77% and specificity 68%. CONCLUSIONS: Most significant prostate carcinoma predictors were PSAD and (F/T)/PSAD, where we proposed that patients with (F/T)/PSAD values below 1.49 ± 0.94 and PSAD values above 0.17±0.06 should be included for biopsy.