The concussion is the second in two NFL seasons for Smith, who was the second overall pick in the 2009 draft.
Coach Steve Spagnuolo said Wednesday team medical personnel and an independent neurologist had no concerns.
Smith bounced back a lot quicker from the latest concussion than he did in his his rookie season, when he missed the final six games.
St. Louis plays Sunday at San Francisco.
Copyright 2010 by The Associated Press