In Major League Baseball, the injured list (IL) (previously referred to as the "disabled list") is a means for teams to remove their injured players from the roster in order to summon healthy players to temporarily replace them. A player may be (but does not have to be) placed on an injured list at any time that he is too injured or ill to play at a league standard, whether the cause of the injury was baseball-related or not. The structure of the various injured lists, and the rules associated with them, have evolved considerably over the decades. The currently existing ones are:
- The 7-day IL. This is only for players who have suffered concussions. The motivation is that 7 days is the average amount of time required for recovering from a mild concussion. The existence of this list encourages teams to not keep concussed players on the active roster.
- The 10-day IL. This is for position players who have suffered any type of illness or injury. Pitchers may not be placed on the 10-day IL.
- The 15-day IL. This is for pitchers who have suffered any type of illness or injury. This list is longer to prevent teams from using "phantom injuries" to rotate pitchers, particularly relief pitchers, in and out of the active roster.
- The 60-day IL. This is for any player who has suffered an injury requiring more recovery and rehab time.
The player may not return to the active roster until the specified number of days has elapsed. However, the player may remain on a list as long as needed for recovery. The way the days are counted is a bit peculiar; the effective date of the listing is counted as day 1, and the player is eligible to be activated on the Nth day. So, for instance, a player who is placed on the 10-day IL with an effective date of May 10 is eligible to be activated on May 19. The effective date is normally the last day that the player appeared in a game. Players may be put on the IL at a date retroactive to the last day he played. This allows a team not to be penalized, beyond the possible disadvantage of playing with a reduced roster, for listing the player as day to day until the gravity of the injury is known. However, back-dating is limited to a maximum of three days. If, for example, a player last played on June 15, but the team doesn't place him on the IL until June 20, then the effective date can only be back-dated to June 17.
If a team's 40-man roster is full, and the team has a player on one of the short IL's who is going to need recovery time, that player can be moved to the 60-day IL. The effective date of the 60-day IL listing will be the same as the original IL listing; thus time already spent on the shorter IL counts towards the 60 days. Teams will sometimes do this if they need to clear a 40-man roster slot.
Sometimes a team will keep an injured player on the roster but listed as day to day meaning the medical staff is unable to determine when the player will be ready for play time and does not want to risk losing the player for two weeks with what might turn out to be a minor injury.
The advantage to placing a player on the IL versus keeping him on the bench, is that it opens up a spot on the active roster, in which another player, usually either another player who has recovered from an injury or a minor league player, can be placed. The advantage inherent to the 60-day IL over the 15-day is that a player on the 60-day list does not count on the team's 40-man roster.
Players on any major league IL continue to receive their major league salary and accumulate major league service time.