In Croatia, Petrinjac families are mainly Croats (from Vrbovec area ), equally Serbs. In the past century, relatively most of Croatian residents bearing this family name were born in Hrvatska Kostajnica area and in Osijek. In Srednja Meminska in Hrvatska Kostajnica area every fourth inhabitant had the family name Petrinjac.
Prevalence
About 30 people with faimily name Petrinjac live in Croatia today, in 19 households. There were 80 of them in the middle of the past century, and their number decreased significantly. They are located in 6 Croatian counties, in 6 cities and 11 other places, mostly in Hrvatska Kostajnica (10), Rijeka (<5), Prnjarovac (<5), Timarci in Hrvatska Kostajnica area (<5), and in Zagreb (<5).
Outside Croatia
At least one family with this surname emigrated from Croatia to the United States. Family name Petrinjac is present in 8 countries on two continents.
In the sources analysed in the project Acta Croatica so far, the name is mentioned over ten times, the first time 1902 in source Hartmann's General List of Apartments in Zagreb.