Polish psychiatrist Maurycy Urstein (1872-1940) is nowadays almost forgotten. He is not mentioned in the history of Polish psychiatry which only partially may be explained by the fact that his most essential works were published in German language. His scientific oeuvre contains dozens of publications, including four monographs on catatonia. Urstein was an ardent advocate of the autointoxication theory of psychiatric disorders, fierce opponent of psychoanalysis and enthusiast of the use of biological methods of treatment in psychiatry. Both some eccentric views and specific personality probably equally contributed to his almost complete isolation among psychiatrists in the interwar Poland.