The article reviews and analyzes the main problems of integration of content of biological education of the students of specialized classes, the functions and levels of integration in the educational process. The problem of didactic integration in secondary school requires theoretical and practical bases in the context of learning and mastering the students basic biological categories and concepts that are the basis for the transformation of biological patterns in the practical application of knowledge. The integrated approach allows integrating knowledge at the methodological and methodical levels, promoting conceptual and semantic-forming structures, revealing common approaches and methods used by different sciences. The level of cognitive processes of the students of specialized classes allows to integrate knowledge, concepts using the transformed teacher’s content at methodological and methodical level. The methodological level determines the outcome of integration - the integrity of knowledge. In the process of integration quantitative and qualitative transformation of interacting elements that contribute to the formation of integrity is carried out. Efficiency promotes the formation of biological knowledge and implementation of improvements in the educational process of all components of educational content on their core level, each of which performs its function in the formation of the pupil: informational; operational; creative search; values and meanings; reflective component; resultant. At the methodological level integration of knowledge is embodied by means of the organizational forms, methods and means of education. The implementation of integrated content of biology is formed through a fundamental conceptual apparatus; interdisciplinary learning ofcognitive activity; information saturation disciplines. The integration of knowledge provides a profile competence, which is an important characteristic quality of graduates of secondary schools and is the ability to consciously apply a set of knowledge, skills and ways of dealing with a range of issues in specialized educational sphere, formation of socially and professionally significant qualities.