Deposition of 90Sr in a bone tissue of the northern mole-vole (Ellobius talpinus Pallas, 1770) living in the head part of the East Ural Radioactive Trace (EURT) (density of pollution by 90Sr 37 MBq/m2 - 1000 Ci/km2) was investigated. Features of the rodent are digging (underground) way of life, family organization of settlements and weak migratory activity. Authentic (p < 0.01) interfamily distinctions in concentration 90Sr are revealed on the background of absence of sexual and are features of accumulation the radionuclides inside separate families, thus individual parameters differ in 7 times. It is established, that the level of accumilation of 90Sr is comparable with that in other species of small mammals in this territory. Age inversion of accumulation of 90Sr earlier found out in other species of mammals on the EURT is confirmed.