The 1991 Philippine Basketball Association (PBA) Third Conference was the last conference of the 1991 PBA season. It started on September 15 and ended on December 15, 1991. The tournament allows one import with a height limit of 6'1" each per team.

Format

The following format will be observed for the duration of the conference:

• The teams were divided into 2 groups.

• Teams in a group will play against each other once and against teams in the other group twice; 11 games per team; Teams are then seeded on the basis on win–loss records. Ties are broken among point differentials of the tied teams. Standings will be determined in one league table; teams do not qualify based on groupings.^[1]
• The top five teams after the eliminations will advance to the semifinals.^[2]
• The Semifinals will be two round-robin affairs with the remaining five teams. Results from the eliminations will be carried over. A playoff incentive for a finals berth will be given to the team that will win at least five of their eight semifinal games.
• The top two teams in the semifinals advance to the best of five finals. The next two teams dispute the third-place trophy in a best-of-three playoff.

Elimination round

Team standings

Semifinals

Team standings

Third place playoffs

Finals