Director of athletics Kirby Hocutt said, via TexasTech.com:
Billy has decided to focus on his health and we wish him a full recovery. We are proud of the young men that he has brought to this campus. Billy's decision allows him to concentrate on his well-being and allows us to turn our attention to preparations for the upcoming season.
Gillispie, who was hired in March 2011, will be paid for the rest of his contract that terminates on April 30, 2013. Associate head coach Chris Walker will take over for now, as the Red Raiders look for an interim head coach for the 2012-2013 campaign.
Gillispie had a rough first season with the Red Raiders, as they went 8-23 (1-17) in the Big 12. A total of 15 players have left the program since he's been head coach, as well as two strength coaches and two directors of basketball operations.
He was accused of mistreatment this month, which allegedly included forcing players to practice, backtracking on promises he made to potential coaching hires and not being straight with players Ty Nurse and Dejan Kravic regarding their scholarship statuses, via CBSSports.com.
The 52-year-old has been head coach of four different programs since 2002, including UTEP, Texas A&M and Kentucky. He led the Wildcats to a combined 40-27 record over two seasons and owns a 148-108 record as a head coach.
Gillispie checked himself into a hospital earlier this month, noting it felt like he had a "stroke" or a "heart attack." He said he had been dealing with a lot of stress.