Fields, the Big 12's Defensive Player of the Year in 2012, will miss TCU's season-opener against LSU at Cowboys Stadium and the Frogs' game against Southeastern Louisiana "due to a violation of university and team policy."
Horned Frogs coach Gary Patterson announced the suspension in a news release.
Fields won the defensive award as a true freshman last season after making 18.5 tackles for loss and 10 sacks. He also forced two fumbles and recovered one as well as logging an interception.
Fields, a native of Arlington, Texas, was TCU's highest-ranked recruit in the class of 2012, but Patterson expressed disappointment in his performance this spring in an interview with ESPN.com last month.
"He's not had as good a spring as we would have liked him to have had," Patterson said. "You just expect him to get better and faster, but if I tell you all the things, then everybody knows about him. The biggest thing is sometimes you don't think you have to work as hard and come back and do some things, so getting him back on the level of why he was the player that he was."