In Croatia, Osojnak families are Croats (from Opatija ). In the past century, relatively most of Croatian residents bearing this family name were born in Rijeka and Opatija.
Prevalence
About 20 people with faimily name Osojnak live in Croatia today, in 13 households. There were 30 of them in the middle of the past century, and their number decreased by 30 percent. They are located in two Croatian counties, four cities and four other places, mostly in Opatija (<10), Matulji in Opatija area (<10), Pobri (<5), Lovran in Opatija area (<5), and in Zagreb (<5).
In the sources analysed in the project Acta Croatica so far, the name is mentioned few times, the first time 1906 in source Yearbook and Directory of Literary Society of St. Jerome 1906.