Aims: Evidence is increasing to indicate that individuals with mental illness may be at risk of premature death. We studied the prevalence of QTc prolongation, QT dispersion (QTd) and cardiac arrhythmias in patients on psychotropic drugs. Study Design: Cross-sectional study. Place and Duration of Study: Department of Medicine and Department of Behavioral Sciences, University of Ilorin Teaching Hospital, Nigeria Between Januaryand June 2010. Methodology: One hundred and ninety-one consecutive patients on psychotropic medications with 121 controls were studied. All the subjects had detailed clinical examination and resting electrocardiogram (ECG) at 25mm/sec. QTc was determined using Bazett formula and QTd by subtracting shortest from longest QTc in 12-lead ECG. Results: Mean QTc of the patients (450±46msc) was longer (p=0.0001) than that of the controls (390±27msc) but mean QTd was similar (p=0.13) in both groups. QTc was prolonged in 68(35.6%) patients compared to 11(9.1%) controls, p=0.0001. LVH, arrhythmias and abnormal T-wave morphology occurred more (p=0.01, 0.01 and 0.001 respectively) in the patients than controls. Age, duration of treatment and total daily doses of antipsychotics were independent predictors of QTc. Cardiac arrhythmias were seen in 24.1% of the patients but none had ventricular arrhythmias. Conclusion: Psychotropic drug use is a risk factor for QTc prolongation and cardiac arrhythmias. We suggest periodic electrocardiography, discourage polypharmacy and recommend drug holiday in stable patients.