Sladonja families are Croats and they are mostly from Pula area. According to some sources they are from Dalmatia. In the past century, relatively most of Croatian residents bearing this family name were born in Pula and in Pula area. In Valtura in Pula area every eighth inhabitant had the family name Sladonja.
Prevalence
About 80 people with faimily name Sladonja live in Croatia today, in 30 households. There were 90 of them in the middle of the past century, and their number decreased by 10 percent. They are located in threee Croatian counties, four cities and four other places, mostly in Valtura in Pula area (50), Pula (15), Zagreb (10), Porec (<10), and in Sroki in Rijeka area (<5).
Outside Croatia
At least eight families with this surname emigrated from Croatia to: the United States (3), Sweden (2), Argentina (2), and to Australia (1). Family name Sladonja is present in this form only in Croatia.
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.