Twice they came from behind, an own goal from Blackburn defender Martin Taylor cancelling out Damien Duff's early strike and substitute Jermain Defoe bursting into the box to equalise Andy Cole's 77th minute goal.
The Hammers suffered a dreadful start. Goalkeeper David James horribly misjudged Duff's shot from the edge of the box and the ball bounced past him to trickle into the net.
James then tipped a Cole header on to the bar in the 22nd minute as Rovers turned the screw.
However, 60 seconds later and they were level as Joe Cole found Steve Lomas and his shot looped off Taylor's outstretched foot and into the corner of the net.
The Hammers spurned numerous chances in the second half as Blackburn boss Graeme Souness went for broke, throwing on Dwight Yorke for full-back John Curtis and switching to a 3-5-2 formation.
Ex-Blackburn player Ian Pearce dragged two good opportunities past the post whilst Trevor Sinclair and Edouard Cisse both should have done better when well placed.
The home team then woke up and began to play their football again. Yorke curled an effort narrowly wide before they took the lead with 13 minutes remaining.
A through ball from Tugay picked out Cole who coolly rounded James to roll home his 150th Premiership goal.
That should have been that, but West Ham came back as slack defending by Rovers gifted them a late equaliser.
Pearce headed down a free-kick and Defoe nipped in front of a sleepy Andy Todd to head home a deserved equaliser for the Hammers.
Blackburn boss Souness said: "It was a poor day, a poor game of football. We are very disappointed, this is as bad as we have played this year."His opposite number Glenn Roeder was delighted with his team's display saying: "This was a great performance. We had a game plan which we stuck to and got level, which we deserved."