In Croatia, Kvaternjak families are Croats (from Vrbovec area ). In the past century, relatively most of Croatian residents bearing this family name were born in Vrbovec area and in Vrbovec. In Hruškovica in Vrbovec area every ninth inhabitant had the family name Kvaternjak.
Prevalence
About 20 people with faimily name Kvaternjak live in Croatia today, in 9 households. There were 30 of them in the middle of the past century, and their number decreased by 40 percent. They are located in only five naselja i to in Zagreb (<10), Brcevec (<5), Krizevci (<5), Vrbovec (<5), and in Ivanja Reka (<5).
Outside Croatia
Family name Kvaternjak is present in two countries.
In the sources analysed in the project Acta Croatica so far, the name is mentioned few times, the first time 1906 in source Yearbook and Directory of Literary Society of St. Jerome 1906.