Objective To investigate the influence of radionuclide cisternography on the accuracy of preoperative diagnosis of normal pressure hydrocephalus and its value in predicting the effect of shunt surgery.Methods The patients who were admitted to the Neurosurgery Department of The 363 Hospital from January 2013 to January 2015 were enrolled. Head MRI scan showed that ventricular dilation was in accordance with the morphological features of hydrocephalus and excluded the factors of obstruction. On admission, the patients were diagnosed with "communicating hydrocephalus", and radionuclide cisternography were performed for all patients after admission.Results A total of 65 patients with ventricular dilation underwent radionuclide cisternography. Among them, 12 patients had no images of radionuclide in the ventricle, but the absorption of radionuclide was normal, and with reference to the symptoms, the diagnosis of hydrocephalus was excluded, and the patients were diagnosed with ventricular dilation rather than hydrocephalus; 53 patients showed radionuclide reflux in the ventricle and significantly delayed absorption of radionuclide and were diagnosed with absorption dysfunction of cerebrospinal fluid, and with reference to the measurement of intracranial pressure and Tap test, they met the diagnostic criteria of normal pressure hydrocephalus(NPH), among whom 47 patients underwent shunting surgery and showed significant improvements in the symptoms such as gait, cognitive function, and urinary incontinence at 6 months after surgery.Conclusions Routine MRI scan is used to obtain a definite diagnosis of most patients with hydrocephalus, but as for patients with ventricular dilation caused by brain atrophy or NPH, if the circulation and absorption of cerebrospinal fluid in the ventricle cannot be clarified, misdiagnosis might occur. Therefore, radionuclide cisternography can be used to assist preoperative evaluation of patients with NPH.