Josh Nunes began the school year as Stanford's starting quarterback. He's ending his career prematurely due to an undisclosed medical condition.
Nunes, who sustained an injury to his bicep muscle late last season, made his decision after missing spring football.
He would have been questionable for the start of the summer camp as well.
Stanford coach David Shaw said previously that Nunes' condition was long term.
Nunes started nine games for the Cardinal and appeared in 10 games. He threw for 1,643 yards and 10 touchdowns on the season.
Geoff Meinken, a fullback, also decided not to return to the playing field because of a knee injury. He will graduate in the spring.