Adolescents who reported to have given sexual favors for payment were investigated. The sample consisted of all adolescents in the public and private school systems in Oslo, the capital in Norway (age group 14-17, response rate 94.3%, N=10,828). Adolescents who had sold sex form 1.4%, three times as many boys as girls. Half the group had done it more than 10 times. Most were under the legal age of sex in Norway (16 years) when this first happened. We found no associations with sociodemographic variables or residential area in Oslo. However, sex sale was associated with low intercourse debut age, conduct problems, alcohol problems, use of drugs (including heroin) and violent victimization. The conclusion is that a small group in the general adolescent population sells sex, and many of the clients are assumed to be homosexual or bisexual men. Adolescents who take part in these activities are often heavily involved in delinquent behaviors and use of drugs, and many probably are in a risk zone for sexually transmitted diseases (including HIV), drug abuse and a delinquent and criminal development.