Scunthorpe were first into their stride with strikers Andy Keogh and Billy Sharp both going close.
Keogh glanced a header just inches wide while Sharp had a close-range shot saved at the second attempt by goalkeeper Stuart Nelson.
But it was Brentford that snatched the lead in the 39th minute when star man Jo Kuffour pounced with a shot from close range after an earlier effort from Thomas Pinault had been blocked on the edge of the six-yard area.
Paul Brooker could have made it 2-0 for the visitors on the stroke of half-time when he broke free into the box and took the ball round goalkeeper Joe Murphy only to see his goalbound shot cleared off the line by defender Dave Mulligan.
Scunthorpe came storming out in the second half in search of an equaliser. Their pressure finally paid off in the 70th minute when Brentford failed to clear an inswinging corner from Ian Baraclough and eventually midfield man John Mousinho headed the ball into his own net.
Scunthorpe renewed their attacking efforts and the visitors found themselves under siege as they were forced to hang on for a point.
Goalkeeper Nelson produced a couple of good saves to turn away efforts from Cleveland Taylor and Matthew Sparrow.
But in the closing stages it was only the woodwork that robbed Scunthorpe of victory no fewer than three times.
First Baraclough bounced a header on top of the bar following a great cross from Taylor. Then there was a double escape for the visitors when Sparrow thrashed a shot against the underside of the bar and a follow-up header from Sharp came back off the post.
Still Brentford could not clear their lines and Sparrow ended up rifling a shot over the top from point-blank range.
Sharp too wasted a chance in stoppage time as Scunthorpe had to settle for a third successive home draw.