Under the guidance of M. M. Kossenko and with her direct involvement the early radiation effects in the population were analyzed, clinical picture of chronic radiation sickness in the observed population was described, the health status of the exposed population and their offsprings was assessed. M. M. Kossenko was engaged in demographic and epidemiological studies of long-term radiation effects in the population of the Urals region, took an active part in the examination and treatment of people exposed to radiation in the Southern Urals and as a result of the Chernobyl accident, participated in joint research of radiation effects in humans led by Russian and foreign scientists.