Jimmy Juan's second-half goal secured bottom-of-the-table Chesterfield a point at Leyton Orient but their winless run extended to 17 matches.
David Mooney, after forcing a reflex save from Tommy Lee, put the hosts ahead from Lee Cook's cross.
Chesterfield substitute Jack Lester inspired an equaliser with his first touch setting up Liam Ridehalgh, whose low, drilled cross was met by Juan.
Jamie Cureton hit the woodwork for Orient in injury time.
VIEWS FROM THE DRESSING ROOM
Leyton Orient manager Russell Slade told BBC London 94.9:
"I thought some of the football we played was really good but I think the disappointment with me and the players and the fans is the result. We should have wrapped the game up.
"We scored one of the best goals I've seen since I have been here. It was a terrific goal, the sad thing is in the first 15 minutes of the second half we didn't build on that.
"The result is frustrating. Three penalty appeals, the first one for me was a penalty. Why don't you give it when someone has got their arm around their neck?"
Chesterfield manager John Sheridan told BBC Radio Sheffield:
"I'm pleased with the way we played the game and I thought we worked very hard. To get something out of the game is very pleasing.
"It's a shame we just can't keep a clean sheet. It's a good point. A point is good but the position we're in three would have been better.
"We defended well as well but the goal's a basic ball in the box. I think it should have been dealt with a lot better."
Leyton Orient 12 Butcher 05 Cuthbert 06 Forbes 11 Chicksen 07 Cox 14 McSweeney 16 Spring 20 Smith 21 Cook (Laird - 68' ) 09 Lisbie (Tehoue - 75' ) 39 Mooney (Cureton - 84' ) Substitutes 02 Ben Youssef 15 Porter 17 Laird 10 Cureton 18 Tehoue Chesterfield 01 Lee 02 Trotman 03 Robertson 12 Ridehalgh 18 Hurst 10 Whitaker 22 Juan 26 Davis Booked 19 Boden 21 Bowery (Lester - 68' ) 25 Talbot Substitutes 13 Fleming 28 Smith 08 Niven 14 Lester 16 Mendy