Socio-medical aspects concerning 193 pregnant patients under the age of 18 were analysed. Of these patients 131 had an interruption of the pregnancy and 62 gave birth to a baby. All the abortion patients were unmarried. The mean age in the abortion group was 16.8 years and in the delivery group 17.2 years. The girls of this study had their first experience of sexual intercourse very early, 32% under the age of 15. The frequency of complications after abortion was 18.5%. In the delivery group the prematurity and prenatal mortality were at least twice as great as in the general population. The girls who gave birth to their babies often came from lower social strata and the relationships in their families were more harmonious than in those who had had abortions. The birth of the baby or the decision to have an abortion is not accidental. The different behaviour patterns have a different background regarding both the personal and the environmental characteristics. The decision of the patient whether to abort or not was influenced by the attitude of the immediate family. The relations between family members were better in the homes of the girls who had a baby than in the homes of those who belonged to the abortion group. In both groups more than 40% of the subjects had suffered the risk of being emotionally deprived because of environmental conditions, including crowded housing and limited economic means. Almost all the subjects knew about the means of prevention, although they may not have had proper instruction and sufficient knowledge of their use. The services given by the goverment to adolescent pregnant patients are insufficient and require immediate attention by society.