Mayo, taken with the third overall pick in the 2008 draft by the Minnesota Timberwolves, said in a statement that the positive test was the result of taking an over-the-counter supplement that contained the banned steroid DHEA (dehydroepiandrosterone).
"I'm extremely disappointed that I'm going to miss the next 10 games, particularly as our club is making a push for the playoffs," Mayo said in a statement.
"I had no idea that the over-the-counter supplement that I took was a substance banned by the NBA.
"It was an honest mistake, but I take full responsibility for my actions.
"I apologies to my fans, teammates and the Grizzlies organization for regrettably not doing the necessary research about what supplements I can put in my body."