Demographic processes play a key role in the formation of the geopolitical picture of the world. Population size, its age structure, growth rates and migration flows have a significant impact on the economic power of states, their military potential and their ability to project power in the international arena. This article examines contemporary and historical views on the significance of demographic factors in the geopolitical competition of countries and the measurement of a state's national power. The study covers both contemporary and historical aspects of the issue. The paper provides a systematic review of the evolution of scientific views on the significance of demographic factors in the geopolitical context. Particular attention is paid to modern methodological approaches to measuring the national power of a state considering demographic indicators. The article offers a critical analysis of existing models for assessing geopolitical influence based on demographic factors and considers their applicability in the context of global demographic transformations. The study also addresses topical issues of the impact of demographic trends on the geopolitical strategies of states in the 21st century, including the problems of population aging, migration processes and demographic imbalances between developed and developing countries. Special attention is paid to the analysis of geopolitical aspects of demographic processes in the works of the outstanding Russian demographer L.L.Rybakovsky. The paper considers the key concepts of the scientist, including demographic security, the geopolitical significance of migration processes, the relationship between demography and spatial development of Russia, as well as the role of demographic policy as an instrument of geopolitical influence.