Bruce Dyer denied Rotherham a slice of history to leave Ronnie Moore's side still searching for their maiden First Division victory of the season.
Rotherham looked on course for the three points they had waited 18 years for after beginning their first campaign at this level since 1983 with two defeats and a draw.
Mark Robins's 16th-minute strike yesterday had looked enough for an historic win as Rotherham had not previously triumphed over bitter Yorkshire rivals Barnsley at Oakwell for 32 years.
But Dyer, who had missed a sitter at the end of the first half, duly made amends 12 minutes from time as the Tykes deservedly salvaged a point, with manager Nigel Spackman a relieved man.
For Robins, who inspired Rotherham to promotion last season with 26 goals, it was his fifth goal in five matches and he is already on target to achieve a similar haul.
The 31-year-old former Manchester United player, who will be key to Rotherham's hopes of survival during what is certain to be a trying and testing campaign this season, needed a brave header to break the deadlock.
Chris Swailes' defence-splitting through ball for Marvin Bryan led to the right wing-back's low cross being whipped off the toes of Robins, who had spells at Norwich, Leicester, Manchester City and Walsall before joining Rotherham, by Chris Morgan.
But from the ensuing corner from captain Kevin Watson, the Barnsley centre-back Brian O'Callaghan could only flick the ball into the path of Robins to head home off the knee of Chris Barker from six yards.
Robins also rattled a stunning 15-yard left-foot half-volley narrowly wide just after the half hour, although Barnsley should have been level four minutes before the break.
Mateo Corbo, a 34th-minute substitute for the injured left-wing Darren Barnard, was the provider with a free-kick from the right-hand edge of the penalty area.
Lee Crooks was first to the ball with a header which hammered against the crossbar, but back into the path of Dyer, who somehow contrived to fire the rebound back over the woodwork from no more than four yards.
Following the interval the visitors, roared on by 3,500 travelling fans in a crowd of 15,552, came under pressure, although such was Rotherham's outstanding defensive work that Mike Pollitt was never truly tested in his goal.
The turning point of the whole match came 15 minutes from time as a Rotherham counter-attack led to a surging run and eventual goal-line cross from Chris Sedgwick.
Alan Lee had the goal at his mercy and a second looked on the cards, but Kevin Miller somehow managed to claw the header from underneath his own crossbar to the astonishment of everyone in the ground.
Four minutes later came Barnsley's breakthrough as Steve Chettle provided a superb cross from the left wing for Dyer to steal in and plant a powerful header beyond the outstretched grasp of Pollitt.
Another Dyer header in the dying moments this time lacked the accuracy of the first as Pollitt safely gathered to ensure the spoils were evenly shared.
Barnsley: Miller; O'Callaghan (Neil, 45), Morgan, Chettle, C Barker (Fallon, 76), Crooks, Donovan, Tinkler, Barnard (Corbo, 33), Rankin, Dyer. Substitutes not used: Marriott, Gorre.
Rotherham United: Pollitt; Bryan, Scott, Hurst, Swailes, McIntosh, Watson, Daws, Sedgwick (R Barker, 75), Robins, Lee (Monkhouse, 75). Substitutes not used: Gray, Branston, Beech.
Referee: P Alcock (Halstead).Reuse content