Ixodes apronophorus Schulze, 1924, the marsh tick, belongs to a group of so-called “neglected” ixodid ticks, which remain underexplored compared to the most well-studied species of the genus Ixodes (I. ricinus, I. persulcatus). In this communication, we analyze and summarize the quantitative data on the abundance of this parasite, its geographical distribution, and the diversity of its small mammal hosts in the region of West Siberia (Asiatic Russia). The analyzed data represent a continuous series of observations made between 1953 and 2007, which constitutes one of the longest timeseries ever studied by acarologists. It is shown that the marsh tick in West Siberia is most common in the northern forest steppe and southern taiga landscape zones, being distributed south of 60° N. Among 24 species of small mammals registered as hosts for I. apronophorus in the studied region, three play the most important role: the European water vole (Arvicola amphibius), the tundra vole (Microtus oeconomus), and the Northern red-backed vole (Clethrionomys rutilus). The data characterizing parasitism of the marsh tick on these three hosts in various landscape zones and subzones are provided. We can report a weak albeit significant negative relationship between the abundances of I. apronophorus and its small mammal hosts. The possible explanation lies in the mismatch between the cycles of abundance characteristic of the tick and its hosts.