Background: Isotretinoin therapy is associated with numerous adverse effects of various systems. Although some cases have been reported, cardiac side effects are rare following isotretinoin treatment. Objective: To investigate the effects of isotretinoin on the cardiovascular system. Methods: Seventy patients with acne vulgaris were enrolled in the study. The patients were treated with a dose of 0.5-1.0 mg/kg per day of isotretinoin. Screening for biochemical and hematologic parameters, heart rate, blood pressure and electrocardiographic parameters were done before treatment and after 3 months of isotretinoin treatment. Results: Heart rate, systolic/diastolic tension and electrocardiographic parameters (P-wave duration and QTc duration) were not statistically different before compared with after treatment. Conclusion: As far as we know, there is no study researching the effect of isotretinoin on P- and QT-wave measurements in the literature. We found that isotretinoin did not affect P- and QT-wave measurement. Further studies with longer periods of follow-up are needed to understand the effect of isotretinoin on the cardiovascular system.