Robinson Cano Suspended 80 Games for Banned Substance

Seattle Mariners superstar Robinson Cano -- one of the best players in baseball --has accepted an 80 game suspension after testing positive for a banned substance.

However, Cano insists he did NOT take steroids or any other performance enhancing drug ... he insists he made a simple mistake when taking a prescribed medication.

"Recently, I learned that I tested positive for a substance called Furosemide, which is not a performance enhancing substance," Cano said in a statement.

"Furosemide is used to treat various medical conditions in the United States and the Dominican Republic."

"This substance was given to me by a licensed doctor in the Dominican Republic to treat a medical ailment."

"While I did not realize at the time that I was given a medication that was banned, I obviously now wish that I had been more careful."

The issue ... Furosemide can be used as a masking agent to hide PEDs -- and that's why it's banned.

The 35-year-old is currently nursing a broken hand which he suffered Sunday when he was hit by a pitch while playing against the Detroit Tigers.

MLB says he will be allowed to start serving his suspension immediately, despite the injury.

The 2nd baseman -- an 8-time All-Star -- is in the middle of a 10-year contract worth $240 MILLION. Many people believe he was headed to the Hall of Fame ... but this could derail that.