1989–90 Cuban National Series

In the 29th season of the Cuban National Series, the postseason format was changed. The league directly matched its two division winners in a best-of-seven series for the league championship, while the two division runners-up played a best-of-five series for third place. A four-team round-robin tournament had previously been used, since the 1985–86 season. The 18 teams of the league, and the regular-season schedule of 48 games, remained unchanged.

Henequeneros of Matanzas Province defeated Santiago de Cuba, four games to two, for the championship. Third place was won by Industriales over Granma.

Eastern zone
Source:

Playoffs

 * Championship: Henequeneros defeated Santiago de Cuba, 4–2 games
 * Third place: Industriales defeated Granma, 3–0 games