Since 1998, the Official Baseball Rules state that a pitcher does not get credit for any outs recorded during an inning in which he is charged with an earned or unearned run.
[1] Orel Hershiser holds the Major League Baseball record of 59 consecutive scoreless innings which began on August 20, 1988 and ended on September 28, 1989, breaking Don Drysdale's record of 58 consecutive scoreless innings in 1968, the "Year of the Pitcher.
The second-longest postseason streak was pitched by Whitey Ford, whose 33 consecutive scoreless innings is a World Series record; Ford broke Babe Ruth's 43-year-old record of 29 scoreless innings.
Christy Mathewson holds the National League record with 28 consecutive scoreless innings in the postseason.
Only Walter Johnson and Luis Tiant have multiple streaks of at least 40 scoreless innings, with two each.