Male hypogonadism occurs in up to 40% of men, with a large proportion that may be undiagnosed and untreated, particularly those with late-onset hypogonadism. The condition is associated with suboptimal sexual, physical and psychological functioning. Testosterone-replacement therapy has been shown to prevent or reverse these secondary health complications, leading to an improvement in quality of life. This paper reviews the pharmacokinetics, clinical efficacy and tolerability of a 1% transdermal testosterone gel (Testogel^®/AndroGel^®: 5 g gel contains 50 mg testosterone as the active ingredient) to evaluate its clinical benefits and adverse effects in the treatment of male hypogonadism. Administration of this transdermal preparation of 50–100 mg of testosterone in 5–10 g gel daily appears to provide an optimal dose to most subjects in achieving testosterone concentrations within the male reference range and provides associated health benefits.