Posilović families are Croats and they are mostly from Sisak area. According to some sources from Kupres, Bosnia. In the past century, relatively most of Croatian residents bearing this family name were born in Sisak area and in Zagreb. In Hromec in Krapina area every sixth inhabitant had the family name Posilović.
Prevalence
About 310 people with faimily name Posilović live in Croatia today, in 130 households. There were 390 of them in the middle of the past century, and their number decreased by 20 percent. They are located in the most of Croatian counties, in 20 cities and 32 other places, mostly in Hromec in Krapina area (70), Zagreb (60), Sisak (25), Desno Zeljezno in Sisak area (20), and in Krapina (15).
In the sources analysed in the project Acta Croatica so far, the name is mentioned over thirty times, the first time 1902 in source Hartmann's General List of Apartments in Zagreb.