In Croatia, Korošić families are almost entirely Croats (from Donji Miholjac area ), barely Slovenes (from Zagreb ). In the past century, relatively most of Croatian residents bearing this family name were born in Osijek and in Donji Miholjac area.
Prevalence
About 40 people with faimily name Korošić live in Croatia today, in 15 households. There were 40 of them in the middle of the past century, and their number remains constant. They are located and threee other Croatian places, mostly in Zagreb (10), Belisce (<10), Slatina (<10), Zasadbreg in Cakovec area (<10), and in Valpovo (<5).
Outside Croatia
Family name Korošić is present in two countries on two continents. The family name "Korosic " is used by small number of people in the United States.
In the sources analysed in the project Acta Croatica so far, the name is mentioned few times, the first time 1942 in source Phone Directory of the Independent State of Croatia 1942.