Aim: The main aims of this study are: to calculate accuracy of sex estimation on human sternum of medieval Croatian population by using discriminant functions made for modern Croatian population; to examine whether there is a difference between sternum measures of the contemporary and medieval Croation samples; to evaluate whether discriminant functions for modern Croatian population can be applied to medieval one. Methods: Osteometric measurements on 57 skeletons, 34 where male and 23 female, of which the sex was previously determined by DNA analysis. The sternum measures of 21 preserved skeletons were inserted in the discriminant functions made for the modern Croatian population to obtain sexing accuracy for men, women and total of medieval Croatian population sample. Results: The measures that showed the highest classification rates for men and women were B, SA and DF measurements, and for women MW and B measurements. For most measurements the sample is small, therefore the classification accuracy is relatively low. There was no statistically significant difference between the modern and medieval Croatian sample, except for CSW1 measurements. The sample was sufficient for calculating accuracy of sex estimation, but not for making standards for medieval population. Conclusion: Discriminant functions for modern Croatian population are not applicable, and it is not advisable to use them on the medieval Croatian population.