Study Design - This is a multi-center, double-blind, placebo-controlled, parallel group, randomized study of DHT-Gel versus placebo gel in male subjects ages 55-80 years inclusive with low serum testosterone and symptoms compatible with the clinical diagnosis of hypogonadism. Total enrollment for this study will be approximately 120 subjects (40 subjects for each treatment group). Subjects will be treated with 35 mg/day DHT, 70 mg/day DHT, or placebo gel for 6 months. All subjects will apply the gel once daily. Up to 9 months of study participation, including up to 2 months of screening and a 1-month follow-up period, will be required by the protocol.