The Iron hit back five minutes after the Tykes went ahead with a cool finish from Argentinian Hugo Colace.
The point was a hard earned reward for Scunthorpe, who produced a dogged resistance as fast-improving Barnsley stretched their unbeaten run to five matches.
The home side were denied an early lead thanks to a fine save from Joe Murphy. A speedy burst forward sent winger Adam Hammill tearing forward and he slipped a well timed pass for Daniel Bogdanovic.
The Malta striker tried to curl his low shot, but Murphy palmed the ball away and Jon Macken was just short of connecting as he followed up.
On the break Scunthorpe menaced down the left with Garry Thompson who beat Stephen Foster but saw his shot blocked.
A Barnsley set-piece threatened the visitors when Hammill's corner brought a header from Ryan Shotton, but Murphy stretched to fingertip over the top. And when an Anderson de Silva cross had the visitors struggling again, Hammill couldn't reach it.
Grant McCann - one of Scunthorpe's hard grafting five-man midfield - evaded Hugo Colace but then drilled his shot wide and David Mirfin headed wide after a corner.
A Foster header from another Hammill corner was blocked and cleared and Cliff Byrne headed away another testing corner from Hammill.
After the restart Carl Dickinson's free-kick struck de Silva but was cleared and Macken produced a clever flick after a Hammill cross but was off-target.
Only a super full stretch save from Luke Steele denied Scunthorpe the lead on 50 minutes when he turned away a curling free-kick struck sweetly by ex-Oakwell midfield man Grant McCann.
Three minutes later the home side went ahead when Bogdanovic held up the ball on the right and curled in a low cross that was slotted home by Colace.
The lead lasted just five minutes and Scunthorpe levelled when Gary Hooper's header hit the inside of the post and Hayes followed up and headed in the equaliser.
And Scunthorpe came close to a late winner when Thompson's low shot was just wide and a McCann free-kick was off-target.