In Croatia, Ivšek families are Croats (from Sisak area ). In the past century, relatively most of Croatian residents bearing this family name were born in Sisak area and in Sisak.
About 10 people with faimily name Ivšek live in Croatia today, in 6 households. There were 20 of them in the middle of the past century, and their number halved. They are located in only five naselja i to in Solin (<10), Desno Trebarjevo in Sisak area (<5), Zagreb (<5), Mravince (<5), and in Kuce (<5).
Family name Ivšek 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 1917 in source List of Dignitaries, Officials and Public Servants of the Kingdom of Croatia-Slavonia.