|Harlequins (19) 26|
|Tries: Care, Hopper Cons: Evans 2 Pens: Evans 4|
|London Irish (13) 20|
|Tries: Short, Fowlie Cons: Geraghty 2 Pens: Geraghty 2|
Harlequins held off a late London Irish fightback to win a close game at Twickenham Stoop, which saw the visitors earn a losing bonus point.
After four Nick Evans penalties had put Quins ahead, scrum-half Danny Care crossed to extend their lead.
James Short replied for Irish before half-time, but Matthew Hopper's second-half try put Harlequins further ahead.
Tom Fowlie's score gave the visitors hope, but Quins held on to secure their first win in four Premiership games.
Evans made no mistake from four first-half penalties and, while Shane Geraghty kicked two in reply to make it 12-6, the home side were able to maintain that crucial six-point advantage for the rest of the match.
England international Care went over for the first try of the game after a good move involving Mark Lambert and Nick Easter.
Irish moved back to within six points when Short took full advantage of a high, bouncing kick, but Hopper extended Quins' lead early in the second half after a good break from Jack Clifford.
Against the run of play, Fowlie scored under the posts to reduce the lead to six-points once again, which was enough to secure the visitors a bonus point in defeat, but they could not find a late try to win the match.
Quins are now eighth, 10 points above 10th-placed London Irish, but nine points adrift of fourth spot.
Harlequins director of rugby Conor O'Shea: "You look at the Premiership, we carry more than everyone, we pass more than anyone, we offload more than everybody, we hold onto the ball more than anyone.
"The cynic will say 'they've been found out'. Well, that's rubbish because we need to be more accurate and technically better, but we want to play with the ball in hand.
"Now, if that is a sin to want to play rugby and not just kick-chase and put pressure on the defence then I think the game has a massive question to ask itself.
"Does it want to be all about glorious kick-chasing and pressure or does it want to see teams play with ball in hand?"
London Irish head coach Glenn Delaney: "What you've got to look at is if teams are going to attack, they're going to have to defend as well and you'll defend any way you can within the laws of the game.
"I think there's also an argument that some teams when they attack have a lot of blockers and a lot of people messing around at the fringes of the ruck trying to interfere with defensive teams.
"It's a bit of a cat and mouse game. The beauty of the game is you can approach it any way you want.
"We had a set-piece dominance today which didn't translate on the scoreboard."
Harlequins: Chisolm; Yarde, Hopper, Sloan, Walker; Evans, Care; Lambert, Ward, Shields, Matthews, Robson (capt), Clifford, Wallace, Easter.
Replacements: Replacements: Monye for R Chisholm (62), Dickson for Care (61), Talei for Matthews (53). Not Used: Buchanan, Marfo, Adeniran-Olule, Trayfoot, Botica.
London Irish: Fenby; Lewington, Fowlie, Sheridan, Short; Geraghty (capt), Steele; Court, Paice, Aulika, Sinclair, Treviranus, Cowan, Guest.
Replacements: Replacements: Griffin for Short (52), Allinson for Steele (48), Parr for Court (61), Halavatau for Aulika (48), Cox for Sinclair (63), Narraway for Treviranus (32). Not Used: Stevens, Noakes.
Referee: JP Doyle