The 1945 South American Basketball Championship was the 12th edition of this regional tournament. It was held in Guayaquil, Ecuador and won by the Brazil national basketball team. Six teams competed, including Colombia in their first appearance. After an experiment with a two-round tournament two years earlier, the 1945 competition returned to a single round format.
Each team played the other five teams once, for a total of five games played by each team and 15 overall in the preliminary round.