The patient was a 71-year-old man who had been treated for Parkinson's disease for 21 years. He was admitted because nocturnal dyspnea occurred several times. Echocardiography revealed congestive heart failure because of combined mitral and aortic regurgitation. Double valve replacement was planned. There was a risk of the occurrence of neuroleptic malignant syndrome (NMS) if his drugs for Parkinson's disease were stopped suddenly, so careful control of drug doses was required. Although the patient developed aggravation of his Parkinson's symptoms, careful observation and adjustment of medications prevented the occurrence of NMS.