Introduction. The prevalence of chronic diseases in adolescence is constantly increasing, especially in the last two decades. Adolescence is a period of important changes: body growth and development, sexual development, development of cognitive abilities, change in family relations and between peers, formation of personal identity and personal system of values, making decisions on future occupation etc. Chronic diseases in adolescence. Chronic disorders affect all development issues and represent an additional burden for adolescents. The interaction between chronic disorders and various development issues is complex and two-way: the disease may affect development, and development may affect the disease. Developmental, psychosocial and family factors are of great importance in the treatment of adolescents with chronic disorders. Chronic disorders affect all aspects of adolescent life, including relations with peers, school, nutrition, learning, traveling, entertainment, choice of occupation, plans for the future. Physicians should keep in mind that chronic diseases and their treatment represent only one aspect of person's life. Adolescents with chronic diseases have other needs as well, personal priorities, social roles and they expect these needs to be recognized and respected. Adolescent health care should be adjusted to the life style of adolescents.