Owing to the changes in the general ecological situation in Russia, livestock losses from ovine anaplasmosis have rapidly increased in recent years. The development of a vaccine against this disease is therefore all the more relevant. A continuous culture of tick cells could be used as an appropriate substrate for producing biomass of the pathogen of ovine anaplasmosis, Anaplasma ovis, for the purpose of manufacturing a cell-cultural inactivated vaccine. Such a continuous cell line of the tick Dermacentor marginatus, the definitive reservoir host of A. ovis, has been obtained by cultivation of homogenized tick eggs on a modified Leibovitz medium L15. The established cell line DM-77 has an undifferentiated phenotype: the cells are rounded, with large nuclei and well-visible nucleoli. By the end of the study, the cell line was passaged eight times and did not express signs of growth rate decrease. The duplication time was 2.8 ± 0.3 days for cultivation in a medium with 10% fetal serum at 32°C.