Petljak families are Croats and they are mostly from Zagreb. In the past century, relatively most of Croatian residents bearing this family name were born in Zagreb and in Vinkovci area.
Prevalence
About 80 people with faimily name Petljak live in Croatia today, in 30 households. There were 80 of them in the middle of the past century, and their number remains constant. They are located in threee Croatian counties, four cities and four other places, mostly in Djurdjekovec (30), Zagreb (20), Kasina (10), Sesvete (<10), and in Samobor (<5).
Outside Croatia
Family name Petljak is present in 8 countries on two continents.
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.