1990–91 Cuban National Series

The 30th season of the Cuban National Series featured a postseason bracket tournament for the first time, with the top two teams from each division qualifying. Semifinals were played as best-of-three series, followed by a best-of-seven final series. Both semifinals were won by division runners-up, with Henequeros then defeating Camagüey to repeat as league champions. The 18 teams of the league were unchanged from recent seasons, as was each team's regular-season schedule of 48 games.

Eastern zone
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