Belonging to an ethnic group can affect both socio-economic status and birth-rate (fertility) of the individual. Thus women of minority ethnic groups usually have a relatively high birth-rate, and they are more often single mothers, have lower education and generally lower socio-economic status. Although numerous international researches confirmed the differences in birth rates between ethnic groups, the relationship between ethnicity and birth rates has almost not been investigated in Croatia. This research analyzed the fertility rates of ethnic groups in the Republic of Croatia as well as the relationship between mother's ethnicity and socio-economic variables: age at birth, education, economic activity, nuptiality and birth order. The birth data from DEM-1 forms were used for years 1998 to 2008 as well as the data from the 2001 Census. The links between the mother’s ethnicity and all of the socio-economic variables was established although the magnitude of this correlation was small. Also, there were significant differences in the fertility rates of ethnic groups. The women of Albanian, Bosniak, Romani and other ethnicities, and to some degree Serbian women as well, had lower socio-economic status while the Romani and Albanian women had high fertility. However, it is not possible to establish a clear relationship between ethnicity and fertility owing to methodological difficulties and the way of keeping vital statistics. The inclusion of the variable ethnicity and the presentation of socio-economic variables according to mother’s ethnicity in the official statistical publications would facilitate future research and enable to create a more efficient demographic and social policy.