Barry Bond hit 73 home runs in 2001 to set the single season home run record.
Mark McGwire had over 70 home runs in one season
Barry Bonds holds the records for most home runs in a season (73) and for a career (762).
Barry Bonds holds the record for career home runs with 762 and the mark for most homers in a season with 73.
Dave Klingman holds the record for most home runs hit during a retirement season. He hit 35 home runs in his 1987 final season.
Prince Fielder (50)
The record for team home runs in a season is held by the 1997 Seattle Mariners who hit 264.
Through the 2008 season, that is Prince Fielder with 50 home runs in 2007.
The most home runs Hank Aaron hit in an MLB season was 47 in 1971.
He holds the major league records for most home runs in a career (762) and most home runs in a season (73).
The single-season record-holder for most home runs in a year is Barry Bonds. He hit 73 home runs in 2001.
Barry Bonds of the San Francisco Giants hit a record 73 home runs during the 2001 season. He also holds the record for career home runs with 762.