The aim of this study was to investigate the risk factors of family structure, personality traits, and other variables among adolescent prostitutes. The subjects comprised 158 adolescent prostitutes in a halfway house as the case group and 65 high school girls as the control group. Data were collected by using questionnaires about demographic information, the Junior Eysenck Personality Questionnaire and the Parental Bonding Instrument. A high rate of tobacco, alcohol and drug use was found in the case group. Numerous factors distinguished the cause-effect relationship among adolescent prostitutes. Of all risk factors studied, maternal protection, paternal care, neurotic characteristics, tobacco use, discontinuous schooling and a dysfunctional family had the most direct effect. These results provide useful information for the evaluation of and interventions with adolescent prostitution.