Tobacco smoking amongst the young is a matter of public health concern because of the immediate and long-term health consequences associated with tobacco use, such as asthma, cancers, and cardiovascular diseases. The purpose of this study was to identify the determinants of smoking initiation among a sample of high school students in Bosnia and Herzegovina. The study was conducted among 198 high school students in Zvornik, Bosnia and Herzegovina, during April 2013. A self-administered, pre-tested, structured, close-ended questionnaire was used for data collection. Fourth grade students mainly initiated smoking in high school (45%), while the majority of third and second grade students initiated smoking in primary school. Among students who smoke, an average duration of the smoking habit was <2 years. A multivariate analysis showed that males were 5.27 times more likely to have initiated smoking. For every unit increase in pro-smoking attitude towards smoking, students were 5.3 times more likely to have initiated smoking. Those with parents and friends who are smokers were 6.106 and 5.175 times, respectively, more likely to have initiated smoking. This study indicates that a high proportion of 15-18 year olds in the town of Zvornik are current smokers. Gender, age, and parent and peer influence were identified as important associations with smoking. Interventions should not only be confined to the secondary school environment but they should also extend to their places of residence so that influences in the home environment and social surroundings that contribute to tobacco use are also tackled.