A 15-years-old female patient with seizure disorder and pervasive developmental disorder was scheduled for dental treatment under ambulatory general anesthesia. She had past history of pneumonia and herpes encephalitis when she was 3 year old. Because of sever mental retardation and behavior disorder, routine laboratory test was substituted with physical exam and medical records of department of pediatrics. A few days before general anesthesia, she showed slight common cold, but pediatric consult had reported that there was minimal risk in general anesthesia. After 4-hour general anesthesia, she became critically sick with high fever, cough and malaise. After 10-day hospitalization with pneumonia and sepsis, she could go home.