PIP: This study estimates the number of child prostitutes (CPs) in Thailand. It is estimated by Mahidol University that CPs amounted to about 36,000 children out of 150,000-200,000 prostitutes. The Center for the Protection of Children's Rights estimates that Thai and foreign child prostitutes aged under 11 years, in 1996, amounted to about 800,000 out of a total 2 million prostitutes. An estimated 20,000 establishments employed about 700,000 sex workers. About 30,000 underground sex establishments registered about 1.3 million sex workers. The Ministry of Public Health estimates that CPs amounted to about 16,276 in 1995. The 3 different estimates vary widely. This study estimates the number of CPs aged under 18 years of age, differentiates between Thai and foreign prostitutes, and accounts for those who entered prostitution prior to the age of 18 years. 16% of the total number of prostitutes may be Thai CPs; 50% may have begun their work under the age of 18. About 30% of total foreign prostitutes may be children; 75% may have entered prostitution as minors. A 1997 census of establishments indicates 7816 sex establishments. Based on field research on underestimation, it is estimated that 18,248 were foreign sex workers in Thailand in 1997, or 20% of the total of 90,915 sex workers. 90% of the foreign sex workers were estimated to be from the Mekong subregion of Myanmar, Laos, Cambodia, and Viet Nam. An estimated 4927 (30%) were CPs. During 1990-97, an estimated minimum 80,000 children and women from the Mekong subregion entered the sex trade. An estimated 18,000 were Thai CPs.