In Croatia, Baj families are Croats (from Zagreb ). In the past century, relatively most of Croatian residents bearing this family name were born in Zagreb.
Prevalence
About 10 people with faimily name Baj live in Croatia today, in 6 households. There were 30 of them in the middle of the past century, and their number decreased significantly. They are located in two Croatian cities only, in Zagreb (<10) and Velika Gorica (<5).
In the sources analysed in the project Acta Croatica so far, the name is mentioned over five times, the first time 1902 in source Hartmann's General List of Apartments in Zagreb.