Although Weber’s relationship with communists has been largely neglected by scholars, the aim of this paper is to argue that these figures play a fundamental role for the Weberian reflection on ethics and politics. Firstly, the author will examine Weber’s statements on the Bolsheviks and Spartacists from 1917 onwards. She will then focus, secondly, on Politics as a Vocation, showing how the revolutionary action of the communists is traced by Weber back to a form of ethic of result that it is possible to call «ethic of the ultimate goal». Finally, she will explain how the reflection on communists is crucial for Weber’s own ethical-political position.