Various imaging modalities are useful in confirming the diagnosis, determining the etiology of adult hydrocephalus, providing intraoperative guidance, and improving the follow-up of patients who have undergone treatment including cerebrospinal fluid (CSF) shunting or endoscopic third ventriculostomy (ETV). These include: conventional X-rays, ultrasonography, computerized axial tomography (CT), magnetic resonance imaging (MRI), and radionuclide shunt patency (SP) imaging. CT scans are performed to obtain a baseline image postoperatively to demonstrate the location of the proximal catheter in the ventricular system, the baseline size of the ventricles, and any postoperative intraventricular hemorrhage. CTs are helpful in diagnosing shunt malfunctions in younger patients. MRI provides excellent multiplanar anatomic definition of the ventricular system, subarachnoid spaces, and brain parenchyma. The SP study is a valuable tool in the diagnosis of shunt malfunction particularly in the idiopathic normal pressure hydrocephalus (iNPH) patient population.