Background: Understanding the health information needs of adolescents is the first step towards providing them with relevant information to aid them in their decision making regarding health issues. Objective: The goal of this study is to assess adolescents' needs, perceptions and sources of health information. Methods: Four hundred sixty-nine high school students in Osijek, Croatia, participated in this study by answering a questionnaire. The collected data were analysed using basic frequency and non-parametric statistical methods. Results: The most popular health topics identified by adolescents in our study were nutrition, diseases, depression, relationships, sexual intercourse and alcohol.Adolescents consider their parents the most reliable personal source of health information (72.0%), while they perceive the Internet as the main non-personal source of health information (29.8%). Adolescents wish to get more education about health issues at school (54.4%). Significant gender differences were found in adolescents' needs, perceptions and sources of health information. Conclusions: It is important to provide adolescents with systematic institutional health education and improve health advisory services and library/information services to assist adolescents in locating health information and resolving their health related questions.