We studied accumulation of mercury in the main natural and urban environments of Karelia, Northwest Russia, and assessed potential sources of mercury in a human body. Methods. A total of 200 samples of soil, vegetation, water, surface water, sediments and fish were collected. An analysis of samples was carried out by cold steam atomic absorption method. Diagrams of mercury distribution in soil, birch leaves and lichens were created. Data on fish consumption by the population of Petrozavodsk and Medvezhyegorsk are studied. The concentration of mercury in fish muscles most consumed in Petrozavodsk and Medvezhyegorsk was estimated. Results. Levels of mercury accumulation in soil and vegetation in the studied settings do not exceed the standards adopted in Russia. The same was observed for mercury concentration in water and sediments. Calculation of mercury intake showed that there is a 3-fold difference in the annual intake of mercury in the human body due to differences in the structure of fish consumption in these cities. Summary. External factors do not lead to higher concentrations of mercury in the main natural and urban environments of Karelia. High concentration of mercury in biological samples of pregnant women in the Medvezhyegorsk district is due to the peculiarities of the diet of the local population - the predominance in the diet of freshwater fish (pike, perch, pike perch) caught directly in the Onega lake. Accumulation, Fish, Human body, Mercury, Natural and urban environments