We report on the assessment of the level of genetic diversity of the capercaillie in Belarus. This species of birds is a valuable biological resource, and also acts as a natural indicator for the state of large forests and the degree of their disturbance by human activities. Two subspecies of the capercaillie —Tetrao urogallus major (C. L. Brehm, 1831) and Tetrao urogallus pleskei (Stegmann, 1926) have been described for Belarus. The first domain of the mitochondrial DNA control region was used as the molecular marker for the study. An additional assessment of the level of genetic diversity of the capercaillie was carried out by calculating the effective size of its population (Ne) in Belarus. We found that the absence of subspecific structure is characteristic for all samples of the capercaillie from Belarus. The data on the intraspecific structure and genetic diversity of the capercaillie from Belarus allows us to considerits population in the central and eastern parts of the country as stable and sustainable. This can be explained by its inclusion in the general phylogeographic structure of birds of the boreal lineage. The low values of the effective population size for the partially isolated capercaillie population from the western part of the country indicate the need for increased attention and further monitoring of that population.