Mučnjak families are Croats and they are mostly from Donja Stubica. In the past century, relatively most of Croatian residents bearing this family name were born in Zagreb and Donja Stubica.
Prevalence
About 200 people with faimily name Mučnjak live in Croatia today, in 80 households. There were 210 of them in the middle of the past century, and their number remains constant. They are located in 8 Croatian counties, in 10 cities and 19 other places, mostly in Zagreb (85), Donja Stubica (15), Stubicke Toplice in Oroslavje area (15), Samobor (15), and in Recica (15).
In the sources analysed in the project Acta Croatica so far, the name is mentioned over ten times, the first time 1902 in source Hartmann's General List of Apartments in Zagreb.