Kosijer families are mainly Serbs and they are mostly from Donji Miholjac area , whereas often Croats (from Karlovac ). In the past century, relatively most of Croatian residents bearing this family name were born in Karlovac and Pakrac. In Kosijersko Selo in Duga Resa area every fourth inhabitant had the family name Kosijer.
Prevalence
About 160 people with faimily name Kosijer live in Croatia today, in 100 households. There were 320 of them in the middle of the past century, and their number halved. They are located in the most of Croatian counties, in 23 cities and 25 other places, mostly in Karlovac (40), Zagreb (30), Vinkovci (<10), Lipik (<10), and in Vojnic in Duga Resa area (<10).
Outside Croatia
At least seven families with this surname emigrated from Croatia to: Germany (3), the United States (2), Sweden (1), and to Australia (1). Family name Kosijer is present in 9 countries on three continents.
In the sources analysed in the project Acta Croatica so far, the name is mentioned few times, the first time 2007 in source Encyclopaedia of Croatian Surnames.