Ray Jones' first-half header sunk play-off chasing Colchester and sealed a crucial victory for struggling QPR.
Rangers moved ahead nine minutes before the break when Lee Cook's left-wing cross was deflected into the path of Jones, who headed in at the near post.
Rangers should have wrapped up the game early in the second half when Kevin Gallen hit the post.
Dexter Blackstock and Jones also came close for the home side but one goal proved to enough for the win.
606 DEBATE: Give your thoughts on the match
QPR manager John Gregory:
"2006 was a year to forget for QPR, and we need to do better this year.
"The Christmas period is tough for the players, and I am grateful for the
effort they put in against a very good Colchester side."
Gregory conceded he could lose teenage goalscorer Jones, saying: "Am I resigned to losing him? Frankly, yes."
Colchester manager Geraint Williams:
"We did not deserve anything from the game. That was as poor as we have looked in attack all season.
"I felt we were a bit negative, and we could not break down their back
QPR: Royce, Bignot, Mancienne, Kanyuka, Stewart, Ward (Baidoo 60), Gallen, Lomas, Cook, Ray Jones (Furlong 75), Blackstock.
Subs Not Used: Cole, Rehman, Bailey.
Goals: Ray Jones 36.
Colchester: Gerken, Halford, Baldwin (Guy 85), Brown, Barker, Garcia, Watson, Izzet (Ephraim 73), McLeod (Jackson 63), Cureton, Iwelumo.
Subs Not Used: Davison, Richards.
Ref: P Walton (Northamptonshire).