Ružička families are mainly Croats and they are mostly from Daruvar area , often Czechs (also from Daruvar area ), very rarely Hungarians. In the past century, relatively most of Croatian residents bearing this family name were born in Daruvar area and in Osijek. In Golubinjak in Daruvar area every seventh inhabitant had the family name Ružička.
Prevalence
About 220 people with faimily name Ružička live in Croatia today, in 90 households. There were 190 of them in the middle of the past century, and their number increased by 10 percent. They are located in the most of Croatian counties, in 22 cities and 16 other places, mostly in Zagreb (40), Daruvar (25), Golubinjak in Daruvar area (20), Pakrac (15), and in Koncanica in Daruvar area (15).
In the sources analysed in the project Acta Croatica so far, the name is mentioned over twenty times, the first time 1902 in source Hartmann's General List of Apartments in Zagreb.