In Croatia, Sem families are generally Croats (from Middle Bosnia ), very rarely Czechs (from Zagreb ), and . In the past century, relatively most of Croatian residents bearing this family name were born in Cazma and Bjelovar.
Prevalence
About 20 people with faimily name Sem live in Croatia today, in 7 households. There were 20 of them in the middle of the past century, and their number remains constant. They are located in only four naselja i to in Zagreb (<10), Vrtlinska (<10), Velika Ludina in Cazma area (<5), and in Cazma (<5).
In the sources analysed in the project Acta Croatica so far, the name is mentioned few times, the first time 1924 in source Emigration Commission Zagreb.