In front of 74,000 spectators at Twickenham, Exiles scored six penalties but never crossed the line in a 28-18 loss.
The result leaves Irish eight points behind Aviva Premiership leaders Northampton and in desperate need of a change of fortune in 2011.
Coach Toby Booth insisted that his side will be working hard to ensure they can finally stop the rot in the New Year.
"We have had a wretched run of results and I won't hide away from the fact but we are only half way through the season," he said.
"We are obviously doing a lot of things to make sure this doesn't continue and still we haven't found the formula. It will be back to the drawing board but we will try not to be too over-reactive.
"The realism of what we have been through has left a scar. But we have to dust ourselves down because it is not going to right itself. We have to look at how and why and when we can do things better and I will certainly not shy away from that challenge."
While Exiles certainly have plenty to work on, they will at least have been buoyed by the performance of Chris Malone at Twickenham.
The Australian scored all 18 points for his team from penalties and was the only bright spark in an otherwise uninspired first-half that saw Harlequins take a 18-12 lead.
Like Exiles, all of Quins' points came through penalties in the opening period