OBJECTIVE: To investigate the relationships between 2nd to 4th digit ratio (digit ratio) and prostate cancer detection rate and biopsy findings, including Gleason score. MATERIALS AND METHODS: In 770 consecutive men aged 40 years or older that presented with lower urinary tract symptoms (LUTS), right hand 2nd and 4th digit lengths were measured prior to PSA determinations, DRE and transrectal ultrasonography (TRUS). Among these, 166 men with a prostate specific antigen (PSA) level ≥ 3 ng/mL or abnormal digit rectal examination (DRE) prospectively underwent prostate biopsies. The relationship between digit ratio and prostate cancer detection rate and biopsy findings was investigated. RESULTS: The study subjects were allocated to two groups by digit ratio (group A: digit ratio < 0.95; n = 420; group B: digit ratio ≥ 0.95; n = 350). Despite similar biopsy rates (22.4% vs. 20.6%, p = 0.544), group A had higher cancer detection rate (46.8% (44/94) vs. 23.6% (17/72), p = 0.002; OR = 2.847, 95% CI = 1.445-5.610). When we analyzed 408 positive biopsy cores (group A: digit ratio < 0.95, n = 282; group B: digit ratio ≥ 0.95, n = 126), group A had higher percentage of core cancer volume (46.7% vs. 37.1%, p = 0.005) and more biopsy cores with high Gleason score (sum of Gleason score ≥ 9: 18/282 (6.4%) vs. 1/126 (0.8%), p = 0.010; primary Gleason score = 5: 12/282 (4.3%) vs. 0/126 (0.0%), p = 0.021). CONCLUSIONS: A lower digit ratio is related to an increased detection rate of prostate cancer, a high percentage of core cancer volume and a high Gleason score.