Nick Evans failed with a last-gasp drop goal attempt as Harlequins and Gloucester Rugby could not be separated in a thrilling ten-try game at Twickenham.
Gloucester led 17-15 at half-time thanks to tries from Jeremy Thrush and James Hook, with Harlequins replying through scores for Marland Yarde and Danny Care.
And this see-saw affair continued after the break as two Henry Trinder interception tries and scores for Nick Easter and Ross Chisholm in reply saw the sides locked at 29-29 after an hour.
Shortly afterwards Laidlaw nudged the Cherry and Whites back in front with a penalty before Cook scored a superb solo try to put Gloucester in control heading into the final ten minutes.
But an Evans penalty and conversion from a second Chisholm score saw the teams locked at 39-39 apiece heading into the closing stages, the Kiwi No.10 just wide with a drop goal attempt with seconds left as they couldn't be separated.
Gloucester headed Twickenham knowing they had lost their last six games at the famous stadium, but started on the front foot as Billy Twelvetrees almost got on the end of a Hook kick into the Quins in-goal area.
But they did grab the first try after seven minutes after Mike Brown fumbled a high ball under pressure from Charlie Sharples and the ball eventually found its way to the latter on the right wing with Thrush hacking on and grounding for his first ever Aviva Premiership Rugby try.
Greig Laidlaw added the conversion but five minutes later Harlequins were also on the board thanks to a Evans penalty.
And five minutes after that Harlequins were in front as they spread the ball wide out right and the England wing was on hand to dot down in the corner, fly-half Evans just wide with the tough conversions.
But Gloucester weren’t about to give up and after Laidlaw had kicked them back in the lead, after James Horwilll was offside, the Cherry & Whites were celebrating a second try after half an hour.
It all started with Harlequins looking to break from deep as Yarde broke away, but Matt Kvesic turned the ball over and Hook ran clear to touch down, Laidlaw converting from wide out on the right.
But again Harlequins went up the other end and replied following some patience play, Care darting over following a impressive line from Jamie Roberts.
Evans converted to bring his tally of points this Aviva Premiership Rugby season to 100 and brings Harlequins to within two points of Gloucester at half-time, although it could have been much worse for the outfit from The Stoop as Laidlaw was wide with a last-gasp penalty attempt after Chris Robshaw had been pinged.
After the break Harlequins looked to regain the lead as George Lowe broke clear, but as they tried to recycle the ball out to the left wing Trinder stole in and ran 80m to score, Laidlaw adding the simple conversion.
Harlequins hit back again, first with Evans and Care breaking down the middle to enable Easter to barge his way over.
And then a great run from Roberts passed Thrush saw him offload to Brown, who in turn set up Chisholm to race over for the Quins bonus point, Evans with the conversion for a 29-24 lead.
But another Trinder interception try – which saw him hobble over the tryline through injury – brought Gloucester back level before Laidlaw hit the left upright with the conversion.
Shortly after the hour mark Chisholm failed to release and Laidlaw put Gloucester back in front with a penalty, and Hook thought he moved the Cherry & Whites further ahead only for the play to be called back for a knock on after Sharples had beaten Evans in a race to a ball over the Harlequins defence.
But on 68 minutes Cook found himself under a Brown kick and stepped by would be tacklers to find his way over the whitewash.
Laidlaw added the extras to hand Gloucester a ten-point lead, but almost immediately Harlequins reduced the arrears with an Evans penalty in front of the posts.
And Evans held his nerve again from a touchline conversion to level the scores at 39-39 with two minutes left after Chisholm had barged his way over on the left wing.
But the veteran couldn’t win it for his side as he saw his last-gasp drop goal sail agonisingly wide.