Teams A total of eighteen teams contested the league, including fourteen sides from the 1965–66 season, one club relegated from the
1965–66 Yugoslav First League and three sides promoted from the third tier leagues played in the 1965–66 season. The league was contested in a
double round robin format, with each club playing every other club twice, for a total of 34 rounds. Two points were awarded for wins and one point for draws.
Trešnjevka were relegated from the 1965–66 Yugoslav First League after finishing in the 16th place of the league table. The three clubs promoted to the second level were
Aluminij,
Bratstvo Travnik and
BSK Slavonski Brod.
League table ==East Division==