The contribution to malacology made by the eminent Russian scientist and traveler, Alexander Theodor von Middendorff (1815–1894) is reviewed. Middendorff’s research is rightly considered the highest achievement of Russian malacology in the 19^th century. It is shown, despite the relatively short timespan of his malacological activity, Middendorff could reach substantial progress in the knowledge of the Russian malafauna, both marine, and continental, and authored more than 15 malacological publications, including a series of fundamental systematic works. Middendorff’s views on taxonomy, variability, and zoogeography of molluscs are discussed, and the research program in malacology, proposed by him, is reviewed as well as the impact of his studies on the further development of malacology in the Russian Empire. The full list of all molluscan taxa described by Middendorff is provided as an “Appendix” to the article.