The paper examines the demographic situation in contemporary Czech society and its roots in the past. In the late 20th century there are two key development trends. Demographic model originated in 195Os (characterized by high fertility rates, high marriage rates (95%), high divorce rates (40%), low marriage age and so on) was left after the decline of socialism and the revival of original interwar model has occurred since early 1990s. The second trend is approximating to the model of reproduction usual in Western Europe. This new ways of reproduction are characterized by postponing the marriage and parenthood, so called informal partnerships or unmarried (consensual) couples are becoming more frequent which also results in a growing number of birth of extra-marital children. The increase of divorce rates occurs and hence both numbers of incomplete families and of households including just one individual constantly grow. The improved medical care and healthier regime have led to longer life expectancies over the last fifteen years. The infant mortality figure has further improved. The author concludes that population development significantly influences current economic, health, legal, environmental and political conditions which create together a social environment where the demographic development occurs.