Kidderminster kept alive their record of never having lost a league game at Orient when Mark Yates fired home a penalty nine minutes from time.
But the game will be remembered more for the battle on the pitch which saw two players sent off and eight more booked.
Orient, unbeaten in 10 league matches at home, need nothing less than a win to keep their slim play-off hopes alive and looked to be on course when Gary Alexander headed home his 12th league goal of the season midway through the first half following Donny Barnard's excellent cross.
The blustery conditions spoilt the game as a spectacle as both sides struggled to create many clear-cut chances.
But the match exploded in the second half when Harriers had a goal ruled out following Dean Keates' challenge on Orient keeper Glenn Morris.
Following a 15 man fracas referee Steve Tanner sent off Orient midfielder David Hunt and Keates.
Kidderminster, who had a couple of penalty appeals turned down, finally levelled from the spot when Glen Morris pulled down John Williams and Yates slotted home to the keepers left.
After the game Kidderminster boss Jan Molby was critical of the official and said: "We had a referee who simply could not handle what was no more than an average game.
"Plenty of bookings were given that would not have been bookings in a netball match let alone football" he fumed.
While Orient manager Martin Ling said: "There were more red and yellow cards that we put passes together.
"It was a bad tempered game and a draw was just about the right result. We worked hard enough and I have no complaints about that but every time we won the ball we simply gave it away again." And the Orient manager had no complaints about the penalty either: "To be honest I thought Kidderminster might have had a penalty before that and I was surprised that our goalkeeper was not sent off."