Abstract Portosystemic shunts (PSS) remain an unrecognized cause of neurological or psychiatric disorders. Here we report 5 patients with neuropsychiatric presentations of PSS. Main presentations encompassed progressive Parkinsonism, organic psychosis, recurrent coma, recurrent delusion, cognitive decline and posterior cortical atrophy. None of our patients had a known history of liver disease and laboratory analyses of liver function were normal or only slightly perturbed. Only 16 similar cases of PSS revealed by neurological or psychiatric symptoms were found in the English literature. Clinical presentations were similar to our patients but asterixis, cerebellar symptoms and spastic paraparesis were noticed in some cases. EEG could be normal or could show non specific slow waves or even, rarely, triphasic slow waves. The most frequent and specific diagnostic features included hyperammonemia, abnormal brain magnetic resonance spectroscopy and visualization of the shunts by ultrasonography or abdominal imaging techniques. Therefore, in otherwise unexplained neuropsychiatric disturbances, ammonia should be routinely measured and, if elevated, a dedicated gastroenterologist or an expert radiologist should be consulted for potential PSS examination. Treatment of the shunts or of the hyperammonemia resulted in marked neurological or psychiatric improvement in all cases.