In Croatia, Sep families are generally Croats (from Zupanja area ), very rarely Serbs, and . In the past century, relatively most of Croatian residents bearing this family name were born in Osijek and Zagreb.
Prevalence
About 50 people with faimily name Sep live in Croatia today, in 20 households. There were 70 of them in the middle of the past century, and their number decreased by 30 percent. They are located in 8 Croatian counties, in 6 cities and 7 other places, mostly in Zagreb (15), Osijek (10), Rakovica in Slunj area (<10), Skrljevo (<10), and in Pula (<10).
In the sources analysed in the project Acta Croatica so far, the name is mentioned few times, the first time 1933 in source Emigration Commission Zagreb.