A 72-year-old male patient with Parkinson's disease referred to the Dental Hospital of Kyushu University, Fukuoka, Japan, presented with movement of an implant-supported prosthesis, slight pain, and purulent drainage from the gingiva in the anterior region of the maxilla, where implants had been placed more than 20 years earlier. He requested that the mobile implant and prosthesis be removed and was in need of implant therapy in his maxilla. In addition to Parkinson's disease the patient had a severe gag reflex, which made treatment difficult. A total of 6 treatments were required. New implants were successfully placed while the patient was under anesthesia (a combination of intravenously administered 3% prilocaine hydrochloride and vasopressin); midazolam was also administered intravenously. The results of this case indicate that use of regional anesthesia in combination with midazolam can be recommended for implant surgery in patients with Parkinson's disease. Intravenous midazolam can be considered the sedative of choice for the surgical treatment of patients suffering from systemic disease.