In Croatia, Sluga families are mainly Croats (from Zapresic area ), rarely Italians (from Porec ), and . In the past century, relatively most of Croatian residents bearing this family name were born in Rijeka and in Zapresic area. In Harmica in Zapresic area every seventh inhabitant had the family name Sluga.
Prevalence
About 60 people with faimily name Sluga live in Croatia today, in 30 households. There were 90 of them in the middle of the past century, and their number decreased by 30 percent. They are located in 6 Croatian counties and 5 other places, mostly in Rijeka (25), Zagreb (10), Tar (<10), and in Senkovec (<10) and Harmica (<5) in Zapresic area.
Outside Croatia
Family name Sluga is present in 23 countries on four continents. The family name "Sluga " is used by some 600 people in the United States , about 400 in Germany , and some 300 people in Argentina. "Slugga " is used by few people in the United States.
In the sources analysed in the project Acta Croatica so far, the name is mentioned over five times, the first time 1906 in source Yearbook and Directory of Literary Society of St. Jerome 1906.