One of the main reasons for the rapid spread of HIV in Asian countries is the massive transmission among sex workers and clients. Therefore, effective interventions to prevent HIV transmission through sex work are necessary. Many efforts have been made to promote condom use in sex work. The most significant approach is the 100% Condom Use Programme. Since its conception in 1989, this programme has been implemented in Thailand, Cambodia, Philippines, Viet Nam, China, Myanmar, Mongolia and Laos PDR, with variations in programme components between countries. The main principle is to promote the practice of "No condom - No sex" in all types of sex work, through collaboration between local authorities, sex business owners and sex workers. Variations include formation of sex workers' self-help groups, peer education and issuance of membership cards by local authorities. Sex workers are empowered when they are able to refuse sex without a condom. In Thailand, the programme has increased the use of condoms in sex work from 14% in early 1989 to over 90% since 1992. The 100% Condom Use Programmes in Thailand and Cambodia, which are being implemented on a nationwide basis, are the main reason for the decline in the HIV epidemic. Scaling-up of activities is taking place in all other six countries.