Two goal Gary Fletcher returned to haunt his former team-mates as Lincoln gave their play off hopes a massive boost.
Fletcher spent two unhappy years at Orient scorning just twice before moving to Lincoln last August.
But he returned with a vengeance with goals at the start of each half to send Leyton Orient crashing to their first home defeat since October.
Lincoln manager Keith Alexander was delighted with the win: "It was very windy and blustery but I thought we were worthy winners.
"We played some good football and controlled the game from start to finish." "We are a good side with good players, " added Alexander who was delighted for Fletcher.
"He is only 22 and has got a lot to offer. That's 14 goals this season and it shows how sharp he is. The first one from an acute angle was an excellent finish." Fletcher was withdrawn on the hour suffering with a back problem but by then he had already won his side the game.
The match was only three minutes old when Fletcher latched on to Ciaran Toner's poor back pass and rounded Orient keeper Glen Morris before slotting home from a tight angle.
Despite playing against the gale force wind Lincoln always looked dangerous and Fletcher put Francis Green through minutes later but he was denied by Morris's excellent save.
Orient's best effort in the first half was a shot from distance by defender Donny Barnard that flew inches passed the post.
But Fletcher stuck again with a solo stike four minutes into the second half when he out paced the home rearguard.
After that the O's tried hard to hit back and skipper Gary Alexander had a trio of efforts one of which was superbly saved by Lincoln keeper Alan Marriott.
Orient boss Martin Ling admitted: "It was a disappointing way to lose our record. It was a non performance but all credit to Lincoln they adapted to the conditions better than us - the wind was horrendous."