A 44-year-old man presented with symptomatic hydrocephalus due to aqueductal stenosis. Endoscopic third ventriculostomy was performed but proved ineffective, so ventriculo-peritoneal shunt using a programmable pressure valve (PPV) was carried out. Subdural hematoma appeared 5 weeks postoperatively and subsequently increased though the pressure setting was maximum. One more valve was implanted in the right chest wall and drainage of the hematoma was performed 2 months after the shunt operation. Adjustment of pressure was repeated. Findings of overdrainage and underdrainage were seen once each afterwards. We followed up the patient with the first valve set at 200 mm H₂O and the second valve set at 60 mm H₂O. Disturbance of memorization improved. The patient was in a stable condition 10 months after the final pressure settings. Flow volume changes were examined under conditions of various pressures in tandemly connected double programmable valves in vitro. When total pressure increased, flow showed a linear decrease that was not associated with the order of the pressure settings. This method of adding one more PPV was effective, and appears to be a useful choice for treating overdrainage.