Abstract
The World War I period had considerable effect on demographic development of all states involved in the conflict. From 1915 on, the departure of a large number of young men to the front began to show its consewuences in the degree of natural change in the civilian population of the Czech Lands.The number of newly wedded couples continued to decline as well as the number of newly born children.
The number of deceased persons slightly rose. The situation can be analysed according to the data about civilian population without the Teschen region which were reconstructed by the State Statistical Office.