Ostroški families are Croats and they are mostly from Varazdin area. In the past century, relatively most of Croatian residents bearing this family name were born in Varazdin and in Varazdin area. In Beletinec in Varazdin area every thirtieth inhabitant had the family name Ostroški.
Prevalence
About 200 people with faimily name Ostroški live in Croatia today, in 70 households. There were 170 of them in the middle of the past century, and their number increased by 20 percent. They are located in 9 Croatian counties, in 11 cities and 19 other places, mostly in Sveti Ilija in Varazdin area (40), Zagreb (30), Varazdin (25), Garesnica (20), and in Podevcevo (15).
In the sources analysed in the project Acta Croatica so far, the name is mentioned few times, the first time 2007 in source Encyclopaedia of Croatian Surnames.