Aim: To determine the influence of antiretroviral (ARV) therapy on the QTC interval amongst HIV-infected patients. Design: Prospective Comparative survey of two population samples Patients and Setting: One hundred and thirty ARV naïve and one hundred and thirty treated HIV-positive patients selected from in and out patient departments of Aga Khan University Hospital underwent clinical evaluation and 12 lead resting ECG between August 2008 and March 2009. Methodology: Eligible HIV-positive patients were conveniently sampled and had a 12-lead electrocardiogram (ECG) performed to determine the QTinterval, corrected for the heart rate by the Bazzet formula. Analysis was then performed to determine the odds of development of a prolonged QTC interval (QTC ≥ 440ms) in the ARV-experienced arm compared to the ARV-naïve arm. Results: One hundred and thirty patients in each of the two study arms’ had ECG assessment of the QTC interval. 16.2% of the patients in the ARV-experienced arm had QTC prolongation compared to 6.9% in the ARV-naïve arm (chi square 5.43, p= 0.01) giving rise to an odds ratio of 2.5 (95% CI 1.01-6.67). Conclusion: ARV use significantly increases the risk of development of an acquired long QTC syndrome by two-and-a-half times.