Aaron Harang participant of 2005 Major League Baseball season
Cincinnati Reds
During the 2003 season, Harang was traded to the Reds along with Joe Valentine and minor leaguer Jeff Bruksch for José Guillén. In 2004, he went 10–9 with a 4.83 ERA for the Reds.
In 2005, Harang led the team in wins (11), quality starts (19), innings pitched (211+2⁄3), and strikeouts (163), all of which were career highs. He became the first Reds pitcher with 200 innings in a season since right-hander Elmer Dessens led the staff with 205 innings pitched in 2001. He received votes for NL Pitcher of the Month in May after going 3–1 with 1.93 ERA over five starts.