High-flying Leyton Orient could only manage a point against Lincoln.
The hosts went ahead in the 18th minute when captain Gary Alexander headed in the rebound after keeper Alan Marriott had parried Matthew Lockwood's drive.
Lockwood almost added a second when his ferocious 30-yard shot shaved a post before Nat Brown had a shot cleared off the line for Lincoln.
Lincoln levelled through Richard Butcher's 70th-minute volley before Marriott saved from Daryl McMahon.
Leyton Orient: Garner, Barnard (Carlisle 19), Zakuani, Miller, Lockwood, Tudor, Easton, Simpson, Keith (McMahon 77), Ibehre (Echanomi 72), Alexander.
Subs Not Used: Morris, Hanson.
Goals: Alexander 18.
Lincoln City: Marriott, Bloomer, Cryan, Foster, McAuley, Beevers, Keates, Brown (Asamoah 52), Butcher, Ryan (Marvin Robinson 56), Birch.
Subs Not Used: Green, Hughes, Molango.Booked: Cryan, Beevers.
Goals: Butcher 70.
Att: 4,837
Ref: B Curson (Leicestershire).