Two girls, 15- and 17-year-old, were consecutively and involuntarily admitted to the local child and adolescent psychiatric hospital with severe first onset psychosis. Due to refractory agitation, ongoing psychosis and insomnia, catatonic features, autonomic instability and the need for one-on-one guidance, the first girl was transferred to the PICU of an academic tertiary hospital and anti-NMDA receptor encephalitis was diagnosed. Given this experience nursing staff suspected, due to similarities in the clinical presentation and course, anti-NMDA receptor encephalitis in the second girl also and this proved to be true. The main clinical features, pharmacological and non-pharmacological treatment strategies and outcomes are presented and discussed. Perhaps, one ought to suspect anti-NMDA receptor encephalitis in every case of severe first onset psychosis with catatonic features.