Objective: Nowadays, Smoking is expanding around the world to younger people, even in Middle East, which is more common among older people. Moreover, the bad effects of smoking on health are more than benefits. Therefore, many organizations are being held to raise awareness about stopping smoking around the world. We aimed to assess the effect of majoring in the respiratory therapy field on students’ smoking habits. Methods: The participating subjects were respiratory therapy students senior and junior A Semi-structured questionnaire that is include the information about the smoker. It administered to 130 participants by using stratified random to select the subjects in proportion to the population. Result: The study examined the prevalence of smoking among respiratory therapy students in Riyadh after majoring. The results of our study have shown that there is no significant difference between senior and junior students regarding their smoking habits. According to result, the majoring on Respiratory therapy has no effect on smoking habit of the students. Conclusion: This study is aimed to investigate the effect of majoring in the respiratory therapy field on students’ smoking habits and we found that there are no significant differences between the senior and junior students regarding their smoking rate. In addition, as the increased number of female students who will graduate from the college of applied medical science, respiratory therapy program, Riyadh. Due to that, there is a need to understand the prevalence among female students. Moreover, we need more studies to evaluate the reasons