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.
1990–91 Cuban National Series Serie Nacional de Béisbol 1990–91
"Cronología: 1991" (in Spanish). Archived from the original on February 26, 2005. Retrieved 2006-10-11. (Note - text is printed in a white font on a white background, depending on browser used.)