Eršek families are Croats and they are mostly from Oroslavje area. In the past century, relatively most of Croatian residents bearing this family name were born in Zagreb and in Oroslavje area. In places Donja Bistra and Oborovo Bistransko in Oroslavje area every tenth inhabitant had the family name Eršek.
Prevalence
About 230 people with faimily name Eršek live in Croatia today, in 90 households. There were 170 of them in the middle of the past century, and their number increased by 40 percent. They are located in the most of Croatian counties, in 12 cities and 12 other places, mostly in Donja Bistra in Oroslavje area (65), Zagreb (60), in Oborovo Bistransko (20) and Gornja Bistra (15) in Oroslavje area, and in Lobor in Zlatar area (10).
In the sources analysed in the project Acta Croatica so far, the name is mentioned over five times, the first time 1902 in source Hartmann's General List of Apartments in Zagreb.