His first winner was Calming Influence, who won the Godolphin Mile.
On 22 April 2013, the British Horseracing Authority disclosed that 11 horses trained by Mahmood al-Zarooni tested positive for anabolic steroids.
All 11 horses were banned from racing and Mahmood al-Zarooni faced disciplinary charges.
[2][3] In June 2021, Al Zarooni announced his return to racing.
[5] His first runner since the ban was Major Cinnamon at Meydan Racecourse on November 4, finishing 12th.