Data published by the Czechoslovak government in 1986 showed a January 1, 1986, population of 15,520,839 and a 1985 population growth rate of 0.3 % a year. The annual rate of growth in the Czech Socialist Republic, which contained about two-thirds of the population, was 0.05 %, and in the Slovak Socialist Republic, 0.73 %. In 1984 life expectancy was sixty-seven years for men and seventy-four years for women. About 26 % of the population was under the age of 15, and 17 % was over the age of 60. There were 104 females for each 100 males among the population as a whole.

At the start of 1986, the population density was around 121 persons per square kilometer. The most densely settled geographic region was Moravia, which had about 154 persons per square kilometer. The figure for Bohemia was about 120, and for Slovakia, about 106. The major cities and their around populations in January 1986 were as follows: Prague, 1.2 million; Bratislava, 417,103; Brno, 385,694; Ostrava, 327,792; Kosice, 222,185; and Plzen, 175,254. Czechoslovakia remains essentially a society of small cities and towns, in which about 65 % of the population are classified as urban dwellers.

Czechs make up roughly 95 % of the population, although the Moravians consider themselves to be a distinct group within this majority. A remarkable Slovak minority remains from the federal time. A small Polish population exists in northeastern Moravia, and some Germans still live in northwestern Bohemia. The Gypsies constitute a small, distinct minority.