Oral isotretinoin is currently the most effective therapy for acne, but is associated with numerous adverse effects. To investigate the cardiac effects of isotretinoin, acne patients receiving isotretinoin for 6 months were studied. Methods Twenty-six patients with acne vulgaris were enrolled in the study. The patients were treated with a dose of 0.8 mg/kg/day of isotretinoin (Roaccutane, Hoffman-La Roche, Basle, Switzerland) for 6 months. All participants were assessed pretreatment and at the third month of therapy with 24-h Holter monitoring of electrocardiography. Results Twenty-two patients completed the study (19 females and three males). Initial 24-h Holter monitoring showed normal sinus rhythm in all patients, with a mean heart rate of 79 beats/min (lowest, 63 beats/min; highest, 97 beats/min). At the third month of therapy, 24-h Holter monitoring showed normal sinus rhythm in all patients, with a mean heart rate of 81 beats/min (lowest, 67 beats/min; highest, 91 beats/min). All patients were in sinus rhythm throughout the recording period. None of the patients had supraventricular tachycardia or atrial arrhythmia. Conclusion In this study, 6 months of isotretinoin therapy significantly improved acne and did not cause any cardiac adverse effects at a dose of 0.8 mg/kg/day.