To evaluate the values of PHI and PI-RADS findings in the early detection and prediction of prostate cancer, as well as their application in clinical trials, especially when values of PSA are in the " grey zone" with negative DRE. The 100 patients, men aged 50 years or older with prostate-specific antigen 4 to 10 ng/ml ("gray zone") and normal digital rectal examination with suspected prostate cancer were examined, who had undergone biopsy and were divided in two groups. A group with no evidence of PCa (non PCa) and the group with PCa.The performance of PHI and mpMRI PI-RADS score was compared to predict biopsy results and, specifically, the presence of clinically significant prostate cancer (csPCa) using multiple criteria. Among 100 subjects, 21 (21.0%) were diagnosed with PC, including 13 (61.95%) with csPC (Gleason≥7). By the threshold of PHI≥36, the sensitivity, specificity, PPV, and NPV to predict PCa were 100%, 68.35%, 45.65%, and 100%, respectively.The best cut-off (PHI) was 42.8% with sensitivity 85.7% and specificity 86.1%. The area under the receiver operator characteristic curve (AUC) of combining PHI and mpMRI was greater than that of PHI alone (0.993 vs. 0.954, p=0.002) and mpMRI alone (0.993 vs. 0.976, p=0.025).Comparing the performance in the identification of clinically significant prostate cancer (csPCa), we found that PHI ≥ 73.04 and PI-RADS score ≥ 4 were able to identify csPCa (Gleason score ≥ 7 (3 + 4)) both alone and added to a base model including age, PSA, fPSA-to-tPSA ratio and prostate volume.If biopsy was restricted to patients with PI-RADS 5 as well as PI-RADS 3 or 4 and PHI≥36.0, 50% of biopsy could be avoided with one csPCa patient being missed.The analyzed correlation between PHI and PI-RADS score was statistically significant (p<0.0001). According to the value of Spearman's coefficient, R=0.748, the correlation is positive, i.e. direct, and they showed that with an increase in the value of the prostatic health index, (PHI) the PI-RADS score increases, and vice versa.The combination of PHI and mpMRI had higher accuracy for detection of csPC compared with PHI or mpMRI alone.