Niemann-Pick disease type C (NP-C) is a rare autosomal-recessively inherited lysosomal storage disorder. It is caused by mutations in the NPC1 (95%) or NPC2 gene. It is a progressive and highly heterogeneous disease, characterized by the presentation of visceral, neurological, and psychiatric symptoms. Apart from the patients that die early from organic failure, most of the patients with juvenile and adolescent/adult onset of the disease, develop neurological and psychiatric symptoms. In some cases psychiatric signs, mostly psychosis, can be the first sign of the disease. A delay in diagnosis is often seen. By describing the case of a 16-year old girl, we would like to highlight current opinion about NP-C disease and resume recent findings on the clinical presentation, diagnosis and treatment. We focus on the psychiatric signs, and most important the specific combinations that are typical for the disease. There is no curative treatment for NP-C. Miglustat is used to modify neurological signs in NP-C.