BACKGROUND Rhabdomyolysis is a condition in which intracellular components are released into the blood and urine. Rhabdomyolysis can be caused by drug-related complications and COVID-19; however, the underlying mechanism is not clear. In this study, we report a case of rhabdomyolysis complicated by COVID-19, in which we presumed that the cause of rhabdomyolysis was related to prior administration of haloperidol by assessment of the drug history and progression of myopathy. CASE REPORT A 52-year-old man with schizophrenia experienced worsening insomnia 10 days before admission. Thus, haloperidol was increased from 1.5 mg to 3 mg once daily, and 2 to 3 days later, he developed hand tremors and weakness. One day prior to admission, the patient suddenly developed severe back pain. Based on the examination, the patient was diagnosed with COVID-19 complicated with rhabdomyolysis. Laboratory findings on admission were as follows: creatine phosphokinase: 41 539 IU/L; urinary myoglobin, 190×10³ ng/mL; and hematuria scale, grade 4. On day 1, he was started on saline infusion; therefore, haloperidol was discontinued. On day 2, the hematuria resolved. On day 5, the tremor, weakness, and back pain had resolved. On day 7, his creatine kinase level was 242 IU/L, and saline was administered. CONCLUSIONS It has been suggested that the onset of COVID-19 can exacerbate haloperidol-induced rhabdomyolysis. Therefore, if there is a complication of rhabdomyolysis and COVID-19, it is important to review the drug history, specifically that of haloperidol. We recommend hydration and discontinuation of haloperidol to avoid acute kidney injury, in addition to treating COVID-19.