Testosterone products comprise a multi-billion dollar industry; however, Health Canada and the United States Food and Drug Administration have issued statements of concern about their safety, and their benefits are unclear. In the first phase of this study, we performed a systematic review of the current evidence for the benefits of testosterone replacement therapy. In the second phase, we analyzed the evidence from randomized controlled trials for the benefits of testosterone replacement therapy (depression, quality of life, erectile function, libido, total testosterone level). In the third phase, we analyzed data for harms (cardiovascular death, myocardial infarction, stroke, newly diagnosed prostate cancer, coronary artery disease or diabetes, serious adverse events, withdrawals due to adverse events, erythrocytosis) from randomized controlled trials and non-randomized studies. In general, most included studies had a short duration and were poorly reported. Additional high-quality research into the long-term safety of testosterone products is needed.