Despite high rates of HIV among male injection drug users, the sexual behaviors of at-risk women in Iran remain unknown. A questionnaire on HIV knowledge and risk behavior was administered in a Tehran nongovernmental organization targeting runaways and other women seeking safe haven. Half (total N = 50) were less than 24 years old; baseline HIV knowledge was high. The few who acknowledged using illicit substances said they used "frequently." Nonresponse rates to questions regarding sexual behavior were high (12 of 50). Half admitted a history of sexual activity; 40% of those reported their first sexual contact with someone other than their husband; three people had multiple partners. Three women reported a history of rape. Zero (97.5% one-sided confidence interval [CI] = 0, 0.17) of 35 women tested positive for HIV or syphilis. This study documents the existence of sexual behavior in a population of Iranian women, represents one of the first attempts at sexual research in the Iranian context, and highlights challenges in surveying this vulnerable group.