Ivanjek families are Croats and they are mostly from Krapina area. According to some sources they are from Czechia. In the past century, relatively most of Croatian residents bearing this family name were born in Zagreb and Krapina.
Prevalence
About 100 people with faimily name Ivanjek live in Croatia today, in 50 households. There were 90 of them in the middle of the past century, and their number increased by 10 percent. They are only located in in 6 Croatian cities and 10 other places, mostly in Zagreb (30), Lepajci (20), Petrinja (20), Skaricevo (<10), and in Hrastovica (<10).
Outside Croatia
Family name Ivanjek is present in this form only in Croatia.
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.