In Croatia, Hajsek families are almost entirely Croats (from Krapina area ), very rarely Serbs. In the past century, relatively most of Croatian residents bearing this family name were born in Zagreb and in Krapina area.
Prevalence
About 50 people with faimily name Hajsek live in Croatia today, in 20 households. There were 20 of them in the middle of the past century, and their number more than doubled. They are located in 6 Croatian counties, in 6 cities and four other places, mostly in Zagreb (30), Krapinske Toplice in Krapina area (15), Gat (<5), Bonaci (<5), and in Sesvete (<5).
In the sources analysed in the project Acta Croatica so far, the name is mentioned few times, the first time 1902 in source Hartmann's General List of Apartments in Zagreb.