This article examines the economic views of Russian economist Nikolai Ivanovich Sieber. His name thoroughly forgotten and little is found in scientific articles devoted to Russian economists of the nineteenth century. I think that the main reason for this neglect lies in his dedication to Marxist economic theory, the study of which is currently paid little attention by researchers-economists. Sieber is, in fact, the first Russian economist, who was able to understand Marx's theory in all its complexity and dialectical interrelatedness. In addition, he thoroughly studied the scientific views of the predecessors of Marx, allowing him to understand the ideological unity of Marxism and classical political economy. However, in this article, the main attention is paid to the question of polemics N.I. Sieber with the populists, in particular with V.P. Vorontsov regarding what should be the way of development of economy of Russia. The essence of the dispute was whether the country to develop, on the basis of objective laws of development, those on the capitalist path, or Russia has its own special path of development. Vorontsov and the populists were supporters of non-capitalist development of the country. They believed that in a predominantly agrarian country, which was Russia, there are no necessary prerequisites for capitalist development. Populists fought for the preservation of peasant communities, cooperatives and spoke against creation of large-scale capitalist production in Russia. Sieber denied populist conception about the special way of development of Russia, and defended the Marxist idea that capitalism is an objective stage of development of society and thus is inevitable.