Sir Alex Fergusonâ€™s team continue to drop points away from home as they have still only won once on their travels this campaign.
Dimitar Berbatov looked to have doubled that record when he scored just before the hour and then moments later struck a post.
But Birmingham kept up the pressure and with a minute remaining a ball into the United penalty area fell kindly, after appearing to hit Nikola Zigic's arm, allowing Lee Bowyer to level.
The Blues have now gone 23 league games since they last defeated United but tonightâ€™s point will feel like a win considering their precarious position on the fringes of the drop zone.
For United it is another two points dropped on their travels to a late equaliser and how they must be regretting Ryan Giggs hitting the woodwork in the first half followed by Berbatov in the second period.
At least the Reds reached Christmas unbeaten for the first time in their history, and will now be concentrating on extending that run into the New Year, with hopefully an improvement on their away form.
Referee: Lee Mason
Venue: St Andrews
Birmingham scorers: Bowyer 89
Man Utd scorers: Berbatov 58
15 Dann (yellow card)
04 Bowyer (yellow card)
07 Larsson (Hleb 69)
08 Gardner (yellow card)
23 Beausejour (Zigic 82)
10 Jerome (Phillips 85)
01 Van der Sar
15 Vidic (yellow card)
21 Rafael Da Silva
08 Anderson (yellow card) (Fletcher 73)
28 Gibson (Hernandez 90+1)