Introduction: Tobacco use remains a significant public health challenge, particularly among young adults and university students. Medical students, as future healthcare providers, not only demonstrate heightened vulnerability to this behavior but also play a crucial role in modeling healthy behaviors within society. However, studies indicate a concerning prevalence of cigarette smoking within this population. Therefore, this study aimed to evaluate the effectiveness of the Theory of Planned Behavior (TPB) in predicting smoking cessation among medical students.Methods: This cross-sectional (descriptive-analytical) study was conducted among medical students at various academic levels at Zahedan University of Medical Sciences. Sampling was performed randomly; first, the number of students in each academic level was determined, and then an equal number of participants were selected from four levels: Basic Sciences, Physiopathology, Stajerey, and Internship, with representation from both genders. Data were collected using a questionnaire designed to assess the predictive power of the TPB model for tobacco use. A sample size of 150 participants was recruited through physical sampling. The questionnaire consisted of two sections: demographic questions and TPB constructs, and it was administered after confirming its validity and reliability. After completion, the relationship between the mean scores of the TPB constructs and smoking behavior was examined. Data were entered into SPSS version 27 and analyzed.Results: The findings revealed that 35.3% of the students were cigarette smokers. However, no significant differences were observed in the mean scores of the TPB constructs—including attitude, subjective norm, social norm, behavioral intention, and perceived behavioral control—between smoking and non-smoking students. Nonetheless, significant differences were found in demographic variables such as marital status and academic level between the two groups.Conclusion: The results suggest that the Theory of Planned Behavior alone may not sufficiently predict smoking behavior among the studied medical students. This could indicate the influence of more complex factors or specific socio-cultural contexts not fully captured by the TPB framework. Thus, it is recommended that future interventions aimed at reducing smoking incorporate contextual and socio-cultural variables alongside the individual-focused factors emphasized by this theory.