Lice (Anoplura) were studied in 2015–2018 in the middle taiga of West Siberia in the territory of the Middle Ob region (Khanty-Mansi Autonomous Okrug–Yugra). Lice were found on 15 species of small mammals, of which the most significant hosts were Alexandromys oeconomus, Microtus rossiaemeridionalis, M. agrestis, Myodes glareolus, and M. rutilus. The louse Hoplopleura acanthopus had the widest host range and was also dominant among all the louse species found on small mammals. The peaks of louse abundance coincided with those of host reproductive activity in late spring and early autumn. In the most common host A. oeconomus, the highest degree of infestation (mainly with H. acanthopus) was recorded in adult males; the corresponding indices were significantly lower in adult females and especially low in young mammals. The population structure of H. acanthopus showed prevalence of females (about 50%) in comparison with males and larvae. Co-parasitism of lice was especially pronounced on adult host specimens. The lice Hoplopleura edentula, Hoplopleura longula, and Polyplax hannswrangeli were recorded for the first time from the studied territory.