He represented the Yugoslavia national basketball team internationally.

Demšar played for Egység from Novi Sad and Crvena zvezda from Belgrade.

In July 1950, he was a member of the Zvezda squad that won an international cup tournament in Milan, Italy.

[4] Demšar coached Vojvodina women's team from Novi Sad.

[5][6] Demšar's wife was Marija Veger (born 1947), a former basketball player who played for Vojvodina and the Yugoslavia national team