Sexual education plays an essential role in teaching youth healthy lifestyles and creating mature relationships. The schools textbooks are the most common educational resource and their content is of utmost importance. Correct information can create preconditions for the empowerment of adolescents in making healthy decisions and avoiding risky sexual behaviour. Purpose of the Study: the evaluation of the content of textbooks in the areas of human sexuality and procreation in order to find out to what extent these textbooks promote healthy lifestyles, positive attitude toward fertility function as well as avoidance of risky sexual behaviour among adolescent students. Research Methods: The study sample consisted of 9 textbooks of biology subject for 12-17 year old students of Lithuania. Content analysis evaluated the extent to which these books demonstrated reliable scientific information and comply with the principle norms, moral values and goals of "The General Programme of Health and sexuality education and preparation for family life" of Lithuania. Findings: All textbooks presented inaccurate information in the areas studied. There is no correct information about human fertility system and fertility awareness, about mechanism of action of hormonal contraception, sexuality is presented mostly as a biological function. The evaluation of textbooks allows stating that the content of evaluated biology textbooks does not comply with the provisions and norms of the "General Programme of Health and sexuality education and preparation for family life" and may be unsuitable for healthy lifestyle education. (C) 2017 Published by Future Academy www.FutureAcademy.org.UK