Hydroxychloroquine (HCQ) has been used for the treatment of novel coronavirus disease cases. However, evidence of efficacy remains limited, and adverse events can be associated with its use. Here, we report a case of a patient with severe COVID-19 who, after being administered HCQ, exhibited a 10-fold increase in serum levels of transaminases, followed by a rapid decrease after HCQ was withdrawn. Considering the significantly increased use of HCQ during the COVID-19 pandemic, this case alerts us to the potential for HCQ to be associated with hepatotoxicity and the need to monitor liver function during HCQ therapy.