Kimberly Mathers is reported to have slit her wrists at the couple's home in Sterling Heights, Michigan late on Friday evening.
She was later treated at a nearby hospital after someone called the authorities around 2300 local time (0300 GMT), according to US TV station ABC.
Mathers was scheduled to be transferred to a psychiatric ward at the hospital for observation.
The incident is the latest controversy to hit Eminem, whose real name is Marshall Mathers.
The US artist has been charged with illegally possessing and brandishing a concealed weapon during an argument with a fellow rapper outside a stereo shop on 3 June in Michigan.
He is also accused, on a different indictment, of assaulting a man in a nightclub car park after allegedly seeing him kiss his wife.
On Friday, ahead of Kimberly's suicide attempt, the rapper appeared at the 44th district court in Michigan where he waived his right to a preliminary hearing.
The judge then forwarded his case the circuit court.
Tour trouble
His brief appearance was eagerly awaited by dozens of fans who turned out to see him.
Many had been outside the court for five hours and their enthusiasm was indicative of the rapper's unblighted popularity.
He has also been playing to full houses on his current Up in Smoke tour - also featuring Dr Dre and Snoop Dogg.
However, here too he has succeeded in ruffling some feathers.
In Detroit, where he performed on Thursday night, the rapper was forced to drop a controversial video from the show after city officials threatened to cut power to the stage and arrest organisers.
The video shows partially nude women and depicts a hold-up in an off-licence in which Snoop Dogg holds a robber and asks the audience: "Should I shoot ... ?".
The Detroit officials were also unhappy at Eminem's plan to carry an unclothed inflatable doll on stage.
The rapper bowed to their demands because, said his lawyer Joel Martin, "it wasn't worth the risk" in view of his court appearance the next day.