PIP: Drug consumption, sexual promiscuity, extreme poverty, and low educational level place street children at high risk of sexually transmitted diseases. A prospective study was conducted of 143 street children attending a sexually transmitted disease clinic in Guatemala City over a three month period in 1991. 11 of the children were aged 7-10 years, 47 were aged 11-14 years, and 85 were aged 15-18 years. 104 were male and 39 female. 26 were illiterate and the rest had incomplete primary educations. All had been sexually abused. Over half had had their first sexual experience with a relative. None had ever used condoms. 101 of the children reported they had 1 or 2 sexual partners each day, 6 had 3 or 4, and 36 had more than 4. 133 reported histories of sexually transmitted diseases, of which 94 cases were ulcerative. 112 of the children had genital herpes, 71 had gonorrhea, 39 had human papillomavirus, 19 had vaginal trichomoniasis, 24 had chancroid, and 6 each had vaginal candidiasis, early latent syphilis, and pubic pediculosis. All the children reported using alcohol, tobacco, or marijuana. All used solvents and most used a variety of other drugs.