In baseball, middle relief pitchers are relief pitchers who commonly pitch in the 6th or 7th innings or in situations where several innings worth of work is required (such as extra innings or when the starter is pulled early in the game). The 8th and 9th innings are generally reserved for specialty pitchers (such a left-handed specialists, setup pitchers or closers) but middle relief pitchers may work these innings as well, especially if the game is not close.

Baseball teams generally keep 3 or 4 middle relief pitchers. Because these pitchers will most often pitch at non-critical points in games (e.g. filling in for a starter who has been roughed up early) and are often expected just to eat up innings rather than pitch effectively, per se, these roles are rarely desired by pitchers. In the Major Leagues, middle relief pitchers are often minor leaguers who are being auditioned for more important roles with the club. Otherwise, the role is usually reserved for pitchers who have been unsuccessful in other roles on the staff.