Aim: In the current study, the impact of smoking cessation with and without bupropion usage on p wave duration and p wave amplitude in lead I has been analyzed. Bupropion, which is an atypical antidepressant with effects on both dopaminergic and noradrenergic systems, is approved in the medical treatment of smoking cessation. Several cardiac side effects have been presented when bupropion is prescribed in smoking cessation. Material and Methods: Our study has a prospective design which has planned to evaluate p wave amplitude in lead I and p wave duration changes of bupropion by comparing smoking patients (n=78) before and after bupropion usage. The patients prescribed bupropion were also compared to ex-smoker group (n=50) who quit smoking without bupropion usage in regard to p wave indices in lead I. Differences in the median values between groups were analyzed using Mann-Whitney U test. Categorical variables were analyzed by chi-square test or Fisher’s exact test. For repeated measurements, paired sample t-test and Wilcoxon signed rank tests were used to evaluate the significance of the difference in parameters with normal and skewed distribution. Results: The study included both seventy-eight (79.5% male) patients under bupropion treatment and fifty (88.2% male) patients stopped smoking without pharmacotherapy. P wave duration was notably higher when compared before and after smoking cessation with bupropion (99.0 ± 15.7 ms vs 96.2 ± 11.9ms; p120 ms was significantly higher in smoking patients. (p=0.014) The frequency of the patients with P wave duration