Topical microbicides are an important, promising but complex HIV prevention technology under development. After 11 disappointing effectiveness trial outcomes of 6 candidate products (some tested as multiple doses and formulations) over the past 20 years, there is renewed optimism that a safe and effective microbicide will soon be available if the recent success of coitally linked use of the antiretroviral-based microbicide, 1% tenofovir gel, is confirmed. Studies of new antiviral agents, novel delivery mechanisms, and combination/multipurpose products that address challenges of adherence, enhance the effectiveness of tenofovir gel, and address sexual and reproductive health needs of men and women, including preventing HIV infection, are already underway.