The article tries to explain the genesis of anti-Semitic riots and pogroms in Rzeszów, Kraków, Kielce, Czestochowa in 1945 and 1946. These pogroms are probably the most painful events in the newest Polish history. The first, historical part of this text is about the ritual murder myth as a spark which lit the flame of anti-Semitic riots. The second, sociological, part considers why the conviction of reality of ritual murder escalated after the World War II. Who were the believers of the myth? What were its social functions?