The problem of the youth’s sexual behaviour is one of the most serious problems. The following juvenile problems have lately become especially urgent: early sexual relationships, pregnancy, abortion, diseases that are spread through sexual intercourse. Thus it is not surprising that the problem of juvenile sexual behaviour receives so much attention in pedagogy. In most cases love is understood as physical satisfaction. It is compared to sex. The true secret of sexual life is not realized properly. The problems of irresponsible sexual behaviour cause a number of other problems that have a negative impact on the future of adolescents. On the basis of the research results it is possible to draw the conclusion that the problem of early sexual experience in Lithuania is becoming more and more urgent. The number of teenagers who have had early sexual experience is increasing. It has been noticed that over a half of pupils who took part in the survey have had sexual relationships. According to the research data, the majority of sexually active adolescents acquired their first sexual experience at the age of 16-17. Most male adolescents have begun their sexual life at the age of 16 and the majority of female adolescents – at the age of 17. Thus, the hypothesis of the research that male adolescents start their sexual life earlier than female ones has been confirmed.