Jason Gilbert Giambi (born January 8, 1971) is a Major League Baseball first baseman and was the MVP award winner in 2000.
Born in West Covina, California, Giambi made his major league debut in 1995 with the Oakland Athletics. Originally utilized occasionally as an outfielder, third baseman and first baseman, he assumed the full-time first base job upon the trade of Mark McGwire to the St. Louis Cardinals in 1997. Giambi also filled the leadership gap left by McGwire's departure, leading the team in 1998 with 27 home runs, 110 RBI and a .295 batting average.
Giambi's ascendency as one of the top left-handed sluggers in the game continued in 1999, when he hit .315 with 33 homers and 123 RBI, but was punctuated by a sensational 2000 season in which he hit .333 with 43 homers, 137 RBI, 108 runs, 137 walks and a .476 on base percentage. Giambi narrowly won the American League MVP award over Frank Thomas. His 2001 season was nearly identical, batting .342 with 38 homers, 120 RBI, 109 runs, 129 walks and a .477 on base percentage. He finished a close second in MVP voting to rookie Ichiro Suzuki. Both years, he led the Athletics to the post-season, both times losing in the American League Division Series to the New York Yankees.
In the off-season after the 2001 season, Giambi became a free agent for the first time. Faced with the tough decision of re-signing with the cash-strapped Athletics and testing the market for a better deal, Giambi eventually signed a seven-year $120-million deal with the perennial contending New York Yankees, a deal which angered many baseball purists and Athletics fans who saw the deal as a further example of money dictating the distribution of talent within the league. New York fans, however, having failed to acquire the talents of Alex Rodriguez and Manny Ramírez the previous off-season, were excited to add a top tier free agent to their already loaded offense.
Giambi continued his slugging ways with New York, hitting 41 homers in both 2002 and 2003, and knocking in 122 and 107 runs respectively. Although his average saw a dip from .314 in 2002 to .250 in 2003, he maintained an on-base percentage over .400 and remains one of the most patient hitters in the majors. Late in 2003 he was named by FBI officers investigating the Bay Area Laboratory Co-operative (BALCO) as being one of the baseball players believed to have received anabolic steroids from trainer Greg Anderson .
Giambi is the brother of fellow major leaguer Jeremy Giambi.
On July 30th 2004, test results confirmed that Jason Giambi had a benign tumor which placed him on the disabled list. He was treated for the tumor, and returned to the team and played in a game on September 14th, his first since July 23rd.
On December 1, 2004, the San Francisco Chronicle announced that it had seen Giambi's 2003 grand jury testimony in the BALCO investigation. In his testimony, he admitted to using steroids from 2001 to 2003, and had injected himself with human growth hormone during the 2003 season. On December 2, 2004 the paper ran a front page story alleging that Giambi had not only injected human growth hormone in his stomach, and testosterone into his buttocks, but that he had rubbed an undetectable steroid known as "the cream" on his body and placed drops of another steroid, called "the clear," under his tongue. In his testimony, Giambi also admitted to believing that he thought he had taken Clomid, a female fertility drug, which doctors reported can aggravate a tumor of the pituitary gland.