This research aims at recognizing the extent of biological books in sexual education concepts of the last three classes of basic education. In order to achieve this following questions got answers: 1- What are the concepts of sexual education that are to be contained in the biological books relevant to the last three classes of basic education stage which are in harmony with teen-agers period? 2-What are the concepts of sexual education mentioned in the biological books required for the last three classes of basic education in Syria and what are their ration?