The ventriculoperitoneal shunt is the mainstay of treatment for hydrocephalus. Despite its widespread use and safety record, it often malfunctions due to complications such as obstruction, breakage, migration and infection. This necessitates a systematic approach to diagnosing the etiology of shunt failure. Any evaluation should begin with an appraisal of the patient’s symptoms. In acute malfunction, nausea, vomiting, irritability, seizures, headache, lethargy, coma and stupor are seen. In chronic malfunction, neuropsychological signs, feeding pattern changes, developmental delay, decline in school performance, headaches and increased head size are often seen. The next step in evaluation is a CT scan of the head to evaluate ventricular size. Prior imaging studies should be obtained for comparison; if the ventricles have enlarged over time, shunt malfunction is likely. If there is no such increase or dilation in the first place, other diagnoses are possible. However, “slit ventricle syndrome” should also be considered. When prior imaging is not available, pumping the reservoir, a radionuclide shuntogram, a shunt tap or even surgical exploration are options. The goals of this paper are to provide an algorithm for evaluating shunt malfunction and to illustrate the radiographic findings associated with shunt failure.