Smoking has been recognized as one of the most important health problems. Thus, several preventive measures have been taken worldwide in order to reduce smoking. For these measures to be effective, the source of the problem should be thoroughly explored. To this end, this study aims to determine high school students' smoking behavior and the factors affecting it. In the gathering of data, an interview form was used which was developed by the researchers in accordance with the directives of Planned Behavior Theory. Interviews were conducted according to problem-based interview method. Data were analyzed by using the qualitative data analysis program MAXqda, and was evaluated by using qualitative content analysis method. Findings of the research show that anti-smoking campaigns have been reflected in students' beliefs towards smoking behavior. Differences between female and male students in terms of the beliefs affecting their smoking behavior were detected. It was seen that having no economic difficulty in accessing cigarettes and the fact that cigarettes are being sold disregarding the age-limit are facilitating factors for students to try smoking.