['Isotretinoin is a widely prescribed drug for the treatment of severe acne. Several adverse cardiac effects due to isotretinoin have been previously reported. However, no data exist on the effects of isotretinoin therapy on QT intervals.', 'To investigate the effects of isotretinoin therapy on QT intervals and QT dispersion, and also to see if it is related to serum lipids, homocysteine and lipoprotein (a) or not.', 'Forty-five patients with severe acne (mean age 21±6 years, range 14-38 years; 26 female) were included in the study. Twelve-lead surface electrocardiograms (ECGs) were acquired at three stages: before therapy and at the ends of the first and sixth months of 0.8 mg/kg/day of isotretinoin therapy. Serum levels of triglycerides, total cholesterol, low density lipoprotein cholesterol, high density lipoprotein cholesterol, very low density lipoprotein cholesterol, homocysteine and lipoprotein (a) were also measured at the day of ECG recordings. Minimum and maximum QT intervals were measured and QT dispersion was calculated.', 'Mean heart rates were similar throughout the isotretinoin therapy. Serum levels of lipids, homocysteine and lipoprotein (a) all increased significantly at the end of the first month and remained significantly elevated at the end of sixth month (P is less than 0.05 for both stages). QT intervals and QT dispersion did not differ significantly throughout the six months of isotretinoin therapy (P is greater than 0.05).'] Does isotretinoin prolong QT intervals and QT dispersion in patients with severe acne : a surprising finding for a drug with numerous side effects?