Sajko families are Croats and they are mostly from Krapina area. According to some sources they are from Semovec near Varazdin or from Kamenicko Podgorje in Ravna Gora. In the past century, relatively most of Croatian residents bearing this family name were born in Zagreb and Varazdin. In Kraljevec Šemnički in Krapina area every second inhabitant had the family name Sajko.
Prevalence
About 530 people with faimily name Sajko live in Croatia today, in 210 households. There were 450 of them in the middle of the past century, and their number increased by 20 percent. They are located in the most of Croatian counties, in 25 cities and 49 other places, mostly in Zagreb (125), Varazdin (70), Novska (20), Zarovnica (20), and in Trnovec in Varazdin area (20).
In the sources analysed in the project Acta Croatica so far, the name is mentioned over twenty times, the first time 1902 in source Hartmann's General List of Apartments in Zagreb.