Objective: To evaluate whether total serum PSA, free-PSA ratio and PSA density have similar diagnostic properties for detecting prostate cancer (PCa) and clinically-significant (cs) PCa in men with normal testosterone compared to men with low testosterone with a prior negative biopsy. Methods: We conducted a retrospective analysis of 3295 men undergoing a 2-year prostate biopsy following a negative prestudy biopsy in the placebo arm of the Reduction by Dutasteride of PCa Events (REDUCE) study. Men were divided in 2 groups based on testosterone level < or ≥300 ng/dL. Diagnostic properties of total serum PSA, free-PSA ratio, and PSA density to predict PCa and csPCa, defined as Gleason score ≥7, were determined for several thresholds and plotted as receiver operator characteristic curves. Results: A total of 603 men (18.3%) had low testosterone. The prevalence of PCa and csPCa was 92 (15.3%) and 27 (4.5%), respectively, for low testosterone men compared to 458 (17.0%) and 138 (5.1%), correspondingly, for normal testosterone men. Total PSA, free-PSA ratio and PSA density showed similar sensitivity, specificity, and accuracy to predict PCa and csPCa among low testosterone men compared to normal testosterone men. Conclusion: Among subjects in a clinical trial with a prior negative biopsy, total PSA, free-PSA ratio and PSA density have comparable diagnostic characteristics for PCa screening in low and normal testosterone men.