Minor-league rosters consist of an Active List (players currently eligible to play) and a Reserve List (the entire roster). Players may be loaned to other minor league clubs, but they must be returned by September 30. Minor-league clubs may place injured players on the disabled list for 7 or 60 days (the Emergency Disabled List). As with players in the majors, players on the minor-league 60-day disabled list do not count against either roster limit. Age restrictions do not apply to players on rehab assignments.

Reserve List roster limits 

• 38 players for AAA clubs, 37 for AA clubs, 35 for A clubs and below
  

Active List roster limits 

• AAA clubs: 24 players.
• AA clubs: 24 players (first 30 days of the season), 23 players (day 31 to August 10) and 24 players (August 11 to the end of the season, including the playoffs).
• A clubs: 25 players, with no more than two players with more than five years of minor-league service time.
• Short-season A clubs: 30 players. No more than 25 players may be used in a single game. As of July 1, the Active List must include at least 10 pitchers. No more than four players may be 23 years old or older. No more than three players may have four or more years of minor-league service time.)
• Advanced rookie clubs: 35 players. No more than 30 players may be used in a single game. As of July 1, the Active List must include at least 10 pitchers. No more than 12 players may be 21 years old or older, and no more than two players may be 23 years old or older. No player may have more than two years as a professional, and no player may have three or more years of minor-league service time.
• Rookie clubs: 35 players. No more than 30 players may be used in a single game. As of July 1, the Active List must include at least 10 pitchers. No more than 8 players may be 20 years old or older, including two drafted players and four undrafted players who are at least 21 years old. No player may have more than two years of minor-league service time.