At least 16 million women over the age of 50 currently experience low sexual desire, with approximately 4 million women exhibiting hypoactive sexual desire disorder (HSDD). Although early research established that testosterone therapy improves sexual desire in postmenopausal women, safer and more efficacious administration routes were explored. Large randomized, double-blinded placebo-controlled studies demonstrate that transdermal testosterone improves sexual function and activity in postmenopausal women with HSDD. Large multi-center Phase III trials further confirm the positive effects of the testosterone patch in the treatment of HSDD. More recent studies are exploring the utility of testosterone gels. Based upon data from two recent clinical relevance studies, physicians can be reassured that postmenopausal women with HSDD report a meaningful benefit with testosterone therapy, and further, women will only continue therapy if they experience a meaningful benefit. Although most trials combined testosterone with estrogen/progesterone therapy, the recent APHRODITE trial examined testosterone alone, showing increased sexual desire with mild adverse events. Concerns regarding the long-term safety profile of transdermal testosterone must be addressed before the FDA will approve a testosterone product for women. Although some fear an increased risk of breast cancer with exogenous testosterone administration, recent studies support the idea that androgens can play a role in suppressing the proliferative effects of estrogen and progesterone. Long-term safety data is now being collected and analyzed and Phase III trials focusing on long-term risks are underway. In the meantime, transdermal testosterone appears to be a safe and effective therapy for postmenopausal women with HSDD [Swanson S, DeRogatis L, Snabes M, Simes S, Zborowski J. Treatment of HSDD in surgically menopausal women: a newly initiated Phase III, randomized, double-blind, placebo-controlled, multi-center study of the safety and efficacy of LibiGel. Presented at the Annual Meeting of the International Society for the Study of Women's Sexual Health, February 22-25, Orlando, FL; 2007].