Two tries from England winger Ruaridh McConnochie saw Bath ease to a bonus-point win over Harlequins in front of around 2,700 fans.
McConnochie crossed in each half as the return of supporters to The Stoop failed to inspire Quins to victory.
Harlequins centre Joe Marchant's try opened the scoring but Bath took control soon after and never let up.
Rhys Priestland kicked 21 points in the victory which keeps the visitors well in the hunt for a top four place.
The home side took the lead when Marchant collected Danny Care's chip-kick and burrowed over, with the try given after consultation with the TMO.
Priestland and Quins fly-half Brett Herron then added two penalties apiece, before Bath pounced on an error to score their opening try.
Matt Symons dropped a restart kick and in-form wing McConnochie took full advantage, with an excellent one-handed finish in the corner.
Their second came four minutes later when second-row Elliott Stooke powered over from close range, with Priestland's conversion stretching the lead.
Cameron Redpath's excellent offload, after committing three defenders, allowed McConnochie space to sprint down the touchline to grab his second, shortly after the break.
Two further Priestland penalties stretched the lead to 21 before Argentinian substitute scrum-half Martin Landajo ghosted past Bath's Jonathan Joseph to dot down.
But just a minute later Bath's Lewis Boyce intercepted a loose pass and raced in from 20 metres for the bonus point.
Quins substitute James Lang added a late consolation to give the home side their third try but the game was already long gone for the Londoners.
Harlequins: Brown; Ashton, Marchant, Tapuai, Earle; Herron, Care; Marler, Baldwin, Kerrod, Symons, Young, Robshaw (capt), Evans, Dombrandt.
Replacements: Gray, Garcia Botta, Collier, Lewies, Lawday, Landajo, Lang, Lasike.
Bath: Watson; Rokoduguni, Joseph, Redpath, McConnochie; Priestland, Spencer; Obano, Dunn, Stuart, Stooke, Ewels (capt), Bayliss, Reid, Faletau.
Replacements: Walker, Boyce, Judge, McNally, Ellis, Chudley, Matavesi, De Glanville.
Referee: Tom Foley
Yellow cards: Jack Walker, Tom Dunn (both Bath)