FORMER Hereford loan player Nicky Nicolau's goal five minutes from time sent the Bulls crashing to their third successive defeat.
Nicolau struck to give Barnet all three points after Hereford substitute Trevor Benjamin had cancelled out Albert Adomah's opener.
The result leaves Hereford four points behind Rotherham, who occupy the third automatic promotion place, ahead of Saturday's match between the sides.
A lively run by Barnet winger Adomah inside the first 30 seconds of the Edgar Street contest threatened the Hereford defence as his cross was well grasped by keeper Wayne Brown.
After that, there were few threats on goal for a prolonged period until Hereford top scorer Theo Robinson saw a low drive saved by Lee Harrison.
The Bees' keeper came to his side's rescue on 28 minutes when Toumani Diagouraga turned and shot following a good cross from Sam Gwynne.
Harrison got a good block to the ball and defender Max Porter completed the clearance by kicking the ball off the line.
A low drive by Adomah flashed past the upright as Barnet, looking to ease their relegation fears, hit back and the visitors underlined their threat when a cross by Jason Puncheon evaded the entire home rearguard until Trent McClenahan booted the ball to safety.
Gary Hooper, on loan from Southend United, and Simon Johnson had shots blocked or saved as Graham Turner's men went after the breakthrough but real chances continued to be hard to come by at both ends.
Brown saved well from an Ismail Yakubu header, before the visitors took the lead six minutes into the second period.
Cliff Akurang's shot ricocheted conveniently into the path of Adomah who slipped the ball past Brown.
Hereford's prospects of getting back into the game looked grim for a while until a double substitution shook things up.
One replacement, Kris Taylor, delivered the corner and another, Benjamin, headed the equaliser.
The goal revitalised Hereford for a spell but they were unable to make the best of their dominance and were made to pay five minutes from time.
A shot by Neal Bishop fell to the unmarked Nicolau and the former Hereford loanee easily beat Brown.
Hereford: Brown; McClenahan, Broadhurst, Beckwith, Collins; Gwynne (Benjamin, 62 min), Smith, Diagouraga, Johnson (Taylor, 62 min); Hooper, Robinson. Subs not used: Ingham, Rose, MacLeod.
Referee: Anthony Taylor (Cheshire).
Attendance: 2,271 (56 from Barnet).
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