In Croatia, Černjak families are generally Croats (from Pula area ), very rarely Bosniaks (from Labin ), and . In the past century, relatively most of Croatian residents bearing this family name were born in Pula and in Vrbovec area.
Prevalence
About 20 people with faimily name Černjak live in Croatia today, in 7 households. There were 20 of them in the middle of the past century, and their number remains constant. They are located in only five naselja i to in Mostari in Vrbovec area (<10), Zagreb (<10), Labin (<10), Liznjan in Pula area (<10), and in Lipik (<5).
In the sources analysed in the project Acta Croatica so far, the name is mentioned over thirty times, the first time 1902 in source Hartmann's General List of Apartments in Zagreb.