Recently, remdesivir was approved by the United States Food and Drug Administration for patients with Coronavirus disease 2019 (COVID-19). We herein describe 3 patients with COVID-19 who showed significant bradycardia and QTc prolongation after remdesivir administration. Bradycardia did not respond to atropine treatment in 2 of the patients, one of whom received theophylline and the other required a temporary pacemaker. Fortunately, the patients’ heart rate and rhythm returned to normal after the discontinuation of remdesivir, albeit it lengthened their hospital stays. Careful monitoring during remdesivir infusion may decrease the risk of adverse cardiovascular side effects.