population of Belarus was 10,151,806; a 2001 estimate was 10,350,194, giving the country a population density of 50 persons per sq km (129 per sq mi). The most notable demographic trend since the 1950s has been the steady migration of the population from the villages to urban centers, and the correspondent aging of the population remaining in the rural areas. In 1959 urban residents accounted for 31 percent of the population; in 1979 they accounted for 55 percent; and in 1999 they accounted for about 74 percent. The most populated cities are Minsk, the capital and largest city; Homyel’; Mahilyow; Vitebsk; Hrodna; and Brest.

Ethnic Belarusians make up more than three-fourths of the country's population. Russians, many of whom migrated to the Belorussian S.S.R. in the 1960s, '70s, and '80s, form the second largest ethnic group. Most of the remainder of the population are Poles and Ukrainians, with a small number of Latvians, Lithuanians, and Tatars. Before World War II, however, Jews constituted the second largest group in the republic (and more than half the urban population); the genocide of European Jewry and postwar emigration nearly eliminated Jews from the republic. Both Belarusian and Russian are official languages. Belarusian, which is central to the concept of national identity, is an East Slavic language that is related to both Russian and Ukrainian, with dialects that are transitional to both. It is written in a Cyrillic alphabet and has loanwords from both Polish and Russian, which is reflective of the region's history. An older form of Belarusian was the official language of the grand duchy of Lithuania, of which present-day Belarus was an important component. Most Belarusians who profess a religion adhere to Eastern Orthodoxy. There is, however, a sizable minority of Roman Catholics, and the Eastern-rite (Uniate) church is experiencing something of a revival after centuries of persecution under tsarist Russia and the Soviet government.