There is a certain paradox inherent in Marx's criticism of morality. On the one hand, he rejects morality as a form of bourgeois ideology which serves mainly to justify the status quo. The status quo in question is one which is mainly detrimental to ordinary working people, while favouring property owners as well as owners of the means of production. In this sense Marx's condemnation of morality resembles his condemnation of religion, which he saw as the opium of the people. On the other hand, Marx employs morally significant language to challenge what he regards as the evils of capitalism and their destructive effects on the working class. It becomes clear from all this that capitalism cannot be seen as purely an economic matter. Insofar as it affects the lives and well-being of people, it is also a moral issue and deserves to be judged accordingly. How Marx steers between his seeming rejection of morality and, at the same time, using it to criticise capitalism is the main concern of this article. In the process, Marx's concept of ideology is explained while the focus and motivation of his social critique is also briefly considered.