Sam Deering rescued a point for Barnet with both goals as they came back from 2-0 down against leaders Chesterfield in Martin Allen's first game in charge.
Deane Smalley put Chesterfield ahead from close range after Craig Davies was twice denied.
Davies made it 2-0 with a superb effort from the edge of the area, but Deering pulled a goal back from 25-yards.
In injury time, Chesterfield keeper Tommy Lee let Deering's hopeful cross drop over his head into the net.
Despite being held, Chesterfield moved 11 points clear at the top of League Two.
Barnet, who appointed Allen for his second spell in charge of the club on Wednesday, are now two points behind 22nd-placed Burton, but have played five games more.
Chesterfield manager John Sheridan told BBC Radio Sheffield:
"I'm disappointed because of the way it's ended up, we all feel as if we've lost the game.
"My defenders dealt with the ugly things and did the ugly things well, I'm just disappointed because both goals on our part were very poor to concede and it's cost us three points.
"We're all disappointed because we're a team, it's not because someone's made a mistake, we'll reflect on it because we could have had three points and it would have put us in a good position."