WHAT IS KNOWN AND OBJECTIVE: Acquired long QT syndrome secondary to drug-induced QT prolongation and torsades de pointes has been reported for antiviral drugs. However, no studies have reported an association between corrected QT (QTc) prolongation and antiviral therapy in patients with novel coronavirus disease (COVID-19). CASE DESCRIPTION: We present two cases from our institution in which patients with COVID-19 experienced QTc prolongation during treatment with antiviral therapy. Lopinavir/ritonavir, together with gender and drug-drug interactions, may have contributed to the induction of QTc prolongation in those patients. WHAT IS NEW AND CONCLUSION: Co-administration of QT-prolonging medications and drugs interfering with the metabolism of those medications must be considered in patients with COVID-19. Careful analysis of electrocardiograms for QTc duration should be performed at baseline and during antiviral therapy to identify individuals at high risk of arrhythmias.