Latitude gradients and secular trends in Europe and North America have been found in the male-female ratio at birth (M/F: male births divided by total births) which is expected to be 0.515. Annual national data for Czechoslovakia and the post-Czechoslovakian (Czech Republic and Slovakia) countries for male and female live births were obtained from the World Health Organisation and analysed with contingency tables. This study analysed 13,123,538 live births. An overall decreasing trend in M/F was found (p < 00001). No latitude gradient was noted. There was an overall deficit of 15,232 male births based on an M/F of 0.515. M/F is declining in this region, despite well developing economies that have resisted the worldwide slowdown. An interplay of several poorly understood factors is likely., Victor Grech, and Literatura 19