It was the second time in the half that he was evaluated for a concussion.
Harvin tried to make a leaping catch in the end zone late in the first half before falling backward and hitting his head on the turf.
Harvin, who had major hip surgery on Aug. 1 to repair a torn labrum, was playing in only his second game of the season and his first game since his season debut on Nov. 17 against Minnesota.
Harvin came out in the first quarter when he took a vicious hit from New Orleans safety Rafael Bush.
On that play, Harvin was the intended receiver on a deep pass from Russell Wilson near the Saints 20-yard line. Just as the ball arrived over Harvin's shoulder, Bush launched into Harvin and hit him with his left shoulder while running full speed.
Busch was flagged for unnecessary roughness as Harvin was face down on the turf. He got up and walked to the sideline, but after an evaluation from the trainers, went to the locker room briefly. Harvin jogged back onto the sideline less than five minutes later and returned to the game.
Harvin caught three passes for 21 yards in the first half and had one carry on an end-around where he gained 9 yards.