Health needs of adolescents were analyzed in the adolescent department of the Sainte-Justine Hospital, Montréal, Canada. These needs concern the disorders resulting from socio-familial disturbances, sexuality, general medical problems, chronic disease and problems associated with excessive and/or illicit use of drugs. Details of the organization of this adolescent unit are given. Just as a branch of medicine devoted to the aged, geriatrics, now exists, it must be recognized that adolescents require a separate branch as well.