Background: The Ural region is highlighted among other Russian regions for its unfavorable radiation situation and complexity of the overall environmental situation. The source of man-made radioactive contamination is the work of the "Mayak" Production Association. A significant radioactive contamination has happened as a result of several radiation incidents in the early period of the company activity and it has affected a territory total area of over 23,000 km² in the Chelyabinsk, Kurgan and Sverdlovsk regions. Our primary aim is to compare the characteristics of Heart Rate Variability among residents of the Ural region, living in the territories with different levels of radioactive contamination. Materials and Methods: The segment of the population exposed to increased radiation exposure amounted to approximately 500 thousand people. We have distinguished three territories in the Urals region to perform a comparative study of environmental factors (the radioactive contamination) on human health. Two of these territories are case territories, which are exposed to environmental hazards, and one of them is the control. Data were collected from 1992 to 1995. Results: To assess the dependence of the state of adaptation abilities of the organism exposed to radiation contamination of the territory, we used the stress index. We determined the statistically significant influence of man-made radioactive contamination of the environment on the functional adaptation of the body. Conclusion: Our study showed the predominance of sympathetic regulation of heart rate, which indicates the tension of adaptation capabilities of the organism for the population living in radioactive contaminated areas.