Lincoln snatched a late equaliser to keep up their bid for a play-off spot.
The Red Imps struggled to break down a hard-working Leyton Orient side and paid the penalty when the O's grabbed a goal out of the blue.
But Lincoln fought back and gained their reward when leading scorer Ben Futcher popped up with an 88th minute leveller. Stuart Bimson fired over a free kick and Futcher rose above everyone to direct his header past Orient keeper Glenn Morris.
Lincoln should have made more of their domination in the opening 45 minutes when Orient were so outplayed they failed to manage a single shot.
Bimson broke down the left in the 12th minute before sending in a left-foot shot which brought a diving save out of Morris.
Mark Bailey then curled a free kick around the Orient defensive wall only for Morris to be well-placed to save.
Orient striker Lee Thorpe was yellow carded for a late tackle with Matt Brazier, Simon Downer and Chris Tate all following him into the book before the half-time break.
Orient were more adventurous in the second half and went close on the hour. Andy Harris put a neat ball into the box but Matt Lockwood's header was well saved by Lincoln keeper Alan Marriott.
Six minutes later Orient went in front when the Lincoln defence only half-cleared a Lockwood corner. The ball came out to Brazier who hit his shot straight into the top corner despite Bailey's desperate effort to clear.
Lincoln switched to an aerial bombardment for the final 20 minutes pushing five men forward.
Morris brought off an excellent save at the feet of substitute Allan Pearce and then Chris Cornelly forced his way straight through the middle of the Orient defence but put his shot wide.
Lincoln manger Keith Alexander said: "We had a lot of the play without really creating much. We looked a yard short of pace but I was pleased with the way we kept going and earned a point." Orient manger Paul Brush said: "We were choked to concede a goal that late on. The players battled hard and showed they are committed to the cause.
“I thought we'd held out against everything Lincoln could throw at us until they got that late goal."