Harlequins (16) 40
Tries: Easter, Camacho, penalty, Guest Cons: Evans 4 Pens: Evans 4
Exeter (6) 13
Tries: Foster Cons: Davis Pens: Steenson 2
Quins number eight Nick Easter made it three tries in four games
Harlequins ran in four tries as they crushed Premiership new boys Exeter with a bonus-point win at The Stoop.
Nick Easter scored Quins' first-half try to earn the home side a 16-6 lead.
Tries by Gonzalo Camacho and Tom Guest, along with a penalty try, aided by Nick Evans' 20-point haul with the boot, earned Quins' first win of the season.
Exeter's only try came in the final minute from Mark Foster, Ryan Davis's conversion adding to Gareth Steenson's two first-half penalties.
But the Chiefs might feel aggrieved at the punishment that came their way from referee Sean Davey, who made the second half particularly one-sided with a host of penalties.
To make matters worse for the visitors, Davey showed yellow cards to scrum-half Aidan Thomas and lock James Hanks, one exactly 10 minutes after the other, which meant Exeter played a quarter of the game a man short.
Boasting two wins from the first three Premiership games, Exeter arrived brimming with confidence, something their hosts found more difficult to generate after collecting a meagre three points from as many games.
But Quins, who had Joe Marler making his Premiership debut at loose-head prop, took the initiative from their own kick-off.
They earned a penalty for offside in the first minute, steered home without fuss by former New Zealand stand-off Evans - the first of eight out of eight with the boot.
Exeter's problems increased when number eight James Phillips was helped off after only six minutes with an ankle injury to be replaced by Chad Slade.
And the pressure told when Quins were awarded another penalty by referee Davey, which Evans again despatched with seven minutes on the clock.
It took Exeter nearly 10 minutes to get some decent ball they could run and, when they did, Quins promptly went offside and conceded a needless penalty.
Steenson made them pay with a precise finish before hitting the post with his next effort after the home side were caught offside. But he did not have to wait long for another shot at goal, levelling matters on 23 minutes.
Within two minutes Evans completed his hat-trick of penalties when Exeter were caught offside in front of their posts.
Harlequins scored their first try after a sweeping succession of phases sparked by Evans and finished from close range by England number eight Easter, whose third try in four games was watched by England forwards coach John Wells.
After Evans converted the try for a 16-6 half-time lead, referee Davey absolutely hammered Exeter penalty-wise in the second half.
First, he sent scrum-half Thomas to the sin-bin for not retreating at a penalty. And, seconds before he was due to come back, lock Hanks was yellow-carded for the very same offence.
In between Evans, easily the best player on the pitch, arrowed over his fifth kick out of five, also converting calmly from the touchline when winger Camacho thundered in on the left for Quins' second try.
The penalties kept coming as Exeter, now forced to play 20 minutes a man short, struggled desperately to stem the tide.
When awarded yet another penalty, Harlequins elected for a scrum, not least because Hanks was missing and, one huge push later, Exeter caved in on their line, Davey awarding a penalty try which Evans converted.
Guest then added his side's fourth try before Foster crossed the whitewash for Exeter's late consolation score.
Harlequins rugby director Conor O'Shea said:
"We've been very frustrated with our start. We needed the win desperately. They are a good Exeter team and there is no question that having two men binned makes a big difference and that cost them.
"We wanted to see where we were after five games and, once we've played a hugely motivated Newcastle next week, we'll have a much clearer picture.
"I was very pleased with young Joe Marler. He spent some time with Jason Leonard and will work with him one-on-one regularly. We should use the former greats more. Although I thought he might take him down the pub first, it was great for the lad to have that level of advice."
Exeter head coach Rob Baxter said:
"We are learning lessons and this was a tough one. A few things contributed to the scoreboard. We didn't turn up in the frame of mind of desperation we've had in previous games, and we did not show ourselves at our best.
"A couple of early injuries and then some poor penalties meant that the referee decided which team he was going to penalise, and we did not make our own lives easy.
"But it will be on our minds for a while. Some of the penalties were fair, some tough, some I'm not sure about until I watch the video."
Harlequins: Brown; Camacho, Smith, Turner-Hall, Lowe; Evans, Care; Marler, Cairns, Johnston, Kohn, Vallejos, Robshaw (capt), Skinner, Easter.
Replacements: Brooker, Jones, Lambert, Browne, Guest, Dickson, Clegg, Chisholm.
Exeter: Arscott; Jess, Sestaret, Rennie, Foster; Steenson, Thomas; Sturgess, Clark, Tui, Hayes (capt), Hanks, Johnson, Scaysbrook, Phillips.
Replacements: Alcott, Moon, Budgen, Gannon, Slade, Poluleuligaga, Davis, McKenzie.
Ref: Sean Davey (RFU).