PIP: Two factors have probably led to the widespread acceptance by the clients of prostitutes in Lamphun Province, Thailand, of using 2 condoms, one on top of the other, during sex. Two condoms are used in about half of all sex acts between prostitutes and their clients despite the absence of any official promotion of multiple condom use in the province. First, the women ask their clients not whether they want to use a condom, but whether they prefer to use one or two condoms. In so doing, the woman implies that her client understands the need for condom use and that most people use at least one condom. A similar tactic would be to ask the client whether he prefers a plain or colored condom, a male or female condom, or which of the two partners should apply the condom onto the penis. Second, there is a perception that double condom protection during sexual intercourse significantly reduces the risks of transmitting and contracting sexually transmitted diseases (STDs) and HIV. Since, in absolute terms, there is only a small increase in the level of protection against STDs and HIV from using 2 condoms, no recommendation should be made to use 2 condoms rather than one. However, the use of 2 condoms should certainly be one of several options prostitutes propose to their clients.