The long-term mortality conditions in Slovakia significantly lagged for demographically most advanced European countries. Mortality is one of the two main demographic processes which in the context of demographic transition undergone significant changes. The interbellum period constitutted for the population development and reproductive behaviour in Slovakia one of the most important developmental period. it is the period in which continued and deepened considerably significant quantitative and qualitative changes in the process of mortality. The aim of this paper is to analyze intensity and character of mortality in Slovakia in interwar period and to describe their changes and development. Special attention is paid to the level and character of infant mortality, differential analysis by age, sex, nationality, religion and causes of death., Branislav Šprocha, Pavol Tišliar., and Obsahuje bibliografii