A controversial Luciano Becchio penalty gave Leeds their first league win against Barnsley since 1998.
Referee Darren Deadman pointed to the spot after Reds defender Stephen Foster fouled Leeds skipper Lee Peltier but the challenge looked to be outside the penalty area. Becchio chipped his spot-kick down the middle of the goal.
Leeds' only other shot on target was a 35-yard effort from Rudolph Austin while Barnsley missed plenty of chances.
Jacob Mellis could have put the visitors 2-0 up in the first 16 minutes when he fired wide from eight yards then volleyed tameley into the arms of Leeds goalkeeper Paddy Kenny after a fantastic David Perkins pass. Kenny denied Marlon Harewood from three yards out when the striker looked certain to score. Kenny denied the Reds again in the last minute when he easily caught John Stones' header.