Late-onset hypogonadism, lower urinary tract symptoms (LUTS) due to benign prostatic enlargement (BPE), and prostate cancer commonly coexist in the aging male. Due to a better understanding of the physiology and impact of testosterone on benign and malignant diseases of the prostate, the view toward testosterone replacement therapy (TRT) in these individuals has changed dramatically over time.This communication evaluates the effects of testosterone on benign prostatic growth and prostate cancer and reviews the evidence for TRT for men with BPE and prostate cancer.A literature review was performed with regards to TRT in men with prostate cancer as well as the effect of testosterone on the growth of benign prostate tissue and prostate cancer carcinogenesis.To evaluate the evidence for an effect of testosterone on the growth of benign prostate tissue and the development of prostate cancer and TRT in men with prostate cancer.TRT does not exacerbate LUTS. Current evidence is lacking but suggests that TRT may not increase the risk of subsequent diagnosis of prostate cancer, and is unlikely to impact recurrence or progression for men with treated prostate cancer, but longer follow-up is needed.There is no evidence to suggest that TRT is contraindicated in men with BPE or effectively treated prostate cancer. Tan RBW, Silberstein JL, and Hellstrom WJG. Testosterone and the prostate. Sex Med Rev 2014;2:112-120.