In Croatia, Jonak families are Croats (from Ilok area ). In the past century, relatively most of Croatian residents bearing this family name were born in Zagreb and in Srijem, Vojvodina.
Prevalence
About 20 people with faimily name Jonak live in Croatia today, in 6 households. There were 10 of them in the middle of the past century, and their number doubled. They are located in only threee naselja i to in Zagreb (<10), Velika Gora (<5), and in Lovas in Ilok area (<5).