Harlequins: (6) 15
Pens: Jarvis 5
Bristol: (8) 8
Tries: Lemi
Pens: Strange
Bristol missed the chance to go top of the Premiership as five penalties from Harlequins fly-half Adrian Jarvis earned victory for the Londoners.
Bristol's David Lemi scored the only try in the first half after receiving a misplaced pass from Quins' Mike Brown and running 80 metres to touch down.
Jarvis sealed victory by scoring in the 52nd, 57th and 70th minutes.
To complete Bristol's misery, skipper Matt Salter dislocated his shoulder and will miss the rest of the season.
Harlequins coach Dean Richards on Mike Brown and Andy Gomarsall's England chances: "Everyone was delighted when we heard Dave Strettle would be playing for England and they understand they will get the recognition if they deserve it.
"Mike Brown did extremely well for us again today and if things aren't going well for England at half-back there's still a place for Andy Gomarsall who's a very experienced operator.
"I was very pleased with our performance. We didn't score a try, which was disappointing, but Bristol have probably the best defensive record in the Premiership and you have to take your hat off to them."
Bristol coach Richard Hill: "Matt Salter dislocated the same shoulder against Harlequins earlier this season and he needs an operation on it now so that's him out for the season.
"It makes our back-row problems even worse with Dan Ward-Smith and Alfie To'oala both
out and the Andrew Blowers signing is looking a good decision now.
"Losing Matt is a big blow. He played great for us last week and with the other two injured he was a key ball-carrier for us. Now we'll be struggling to find big powerful runners to carry the ball."
Harlequins: Brown; Keogh, Luscombe, Deane, Monye; Jarvis, Gomarsall; Croall, Fuga, Ross, Kohn, Evans, Vos, Volley (capt), Easter.
Replacements (from): Richards, Nebbett, Spanghero, Skinner, So'oialo, Williams, Duffy, Turner-Hall.
Bristol: Taumalolo; Robinson, Brew, Higgitt, Lemi; Strange, O'Riordan; Clarke, Regan, Crompton, Winters, Llewellyn, Budgett, El Abd, Salter (capt).
Replacements: Blaney, Hobson, Hohneck, Pennycook, Gray, Cox, Morgan.