: The aim of this study was to determine the knowledge, attitudes, and practices of family physicians and pediatricians in regard to adolescent immunization.: The study was conducted from March to May 2017. A total of 665 physicians participated. Participants were asked 31 questions about their personal sociodemographic characteristics and their knowledge, attitudes, and practices around adolescent immunization.: The study sample consisted of 348 family physicians (52.3% of the sample) and 317 pediatricians (47.7%). The results showed that 5.4% of family physicians and 10.4% of pediatricians thought that they had enough knowledge about adolescent immunization ( < .01). Overall, 15.8% of family physicians and 12.7% of pediatricians provided adolescents with information about vaccines 'always/most of the time'. A variety of reasons for not providing information about adolescent vaccines was provided, including 'inability to allocate time' (50.2% of family physicians, 69.3% of pediatricians); 'forgetfulness' (34.8% of family physicians, 28.5% of pediatricians); 'lack of knowledge about vaccines' (34.1% of family physicians, 27.4% of pediatricians); and 'no need to immunize adolescents' (15.7% of family physicians, 6.5% of pediatricians) ( < .01). HPV immunization was recommended only to girls by 30.5% of family physicians and 38.8% of pediatricians ( < .01). The percentages of family physicians and pediatricians not recommending that adolescents be immunized with the Tdap vaccine were 53.4% and 42.6%, respectively ( = .016). Meningococcal immunization was not recommended by 20.7% of family physicians and 11.4% of pediatricians ( < .01), and influenza immunization was not recommended by 10.3% of family physicians and 8.2% of pediatricians ( < .01).: Family physicians and pediatricians in Turkey have low rates of recommendation of immunization to adolescents. Reasons for not recommending immunization include an inability to allocate time, forgetfulness, and lack of knowledge about vaccines. We conclude that educational programs should be used to improve knowledge of adolescent immunization among family physicians and pediatricians.