The Office of the Commissioner of Baseball announced Friday that Bynum, a 29-year-old second baseman, has received the 50-game ban after testing positive for a performance-enhancing substance in violation of the Minor League Drug Prevention and Treatment Program.
The suspension is effective immediately.
Bynum was struggling in his seventh Minor League season, batting .248 with four homers and 17 RBIs in 29 games. He was hitless in his last three games and was batting .211 against right-handers this year.
The Indiana University product was originally selected by the Montreal Expos in the 2003 Draft. His best season came in 2008 when he hit 21 homers and totaled 79 RBIs between Class A Advanced Potomac and Double-A Harrisburg.
The Louisville, Ky. native made his Triple-A debut in 2009, when he hit .262 with 19 homers and 67 RBIs in 134 games as an IL All-Star for the Chiefs.
Bynum is the 23rd player suspended this year under the Minor League drug program.