In Croatia, Rošer families are predominantly Croats (from Banja Luka Region (Bosnia) ), rarely Bosniaks (from Rijeka ), and . In the past century, relatively most of Croatian residents bearing this family name were born in Banja Luka Region, Bosnia (Banja Luka area) and in Middle Bosnia (Sarajevo area).
Prevalence
About 10 people with faimily name Rošer live in Croatia today, in 7 households. There were 0 of them in the middle of the past century, and their number multiplied. They are located in only four Croatian places: in Rijeka (<10), Okrug Gornji on the Island of Ciovo (<5), Rogoznica in Trogir area (<5), and in Gornji Humac on the Island of Brac (<5).
In the sources analysed in the project Acta Croatica so far, the name is mentioned over ten times, the first time 1917 in source List of Dignitaries, Officials and Public Servants of the Kingdom of Croatia-Slavonia.