San Francisco 49ers quarterback Alex Smith has been declared out for Monday night's game against Chicago with a concussion.
Team medical director Dr. Dan Garza evaluated Smith, who was hurt eight days ago against St. Louis.
The 49ers will start second-year quarterback Colin Kaepernick, who replaced Smith in the 24-24 tie with the Rams last week.
Chicago also is without starting quarterback Jay Cutler because of a concussion. Jason Campbell will start.