The history of the Russian Revolution dominated Marxist and radical politics throughout the twentieth century. It also set the context for intense political and theoretical juxtapositions. In particular, the interpretation of the class character of the Soviet Union gave rise to much controversy and was inseparably linked with the issue of Stalinism. Yet, what was highly problematic in most of these approaches was that their positions reflected the political expediencies, sectarianism and dogmatism of the fragmented labour movement. Thus, they failed not only to function in a situation of mutual recognition, critical solidarity and open criticism, but also to provide a radically satisfactory answer to the Russian question. Unfortunately, even in present-day critical theory and within the radical movement, it appears that the questions concerning the nature of Stalinism do not attract much attention. As a result, liberals and conservatives have been able to appropriate the history of the Russian Revolution by presenting the tragedy of Stalinism as the absolute and irredeemable failure of socialism. More importantly, the inability of the anti-capitalist movement to draw the necessary and inescapable conclusions from its own past struggles and failures constrains the formation of a radical alternative to capitalism. This paper argues that the Soviet experience and the issue of Stalinism need an imperative and much more careful and critical rethinking. There is within the radical tradition a valuable theoretical legacy that has to be reconsidered and further developed. To this end, the aim of this article is to discuss the critique of Stalinism provided by Anton Pannekoek and Cornelius Castoriadis. It explores their short exchange of letters on this topic and proceeds analytically to outline their positions in regard to the Stalinist phenomenon. The paper concludes by critically examining the limits and the merits of their approaches.