Bradford (22) 44
Tries: Vainikolo 3, Vagana, Deacon, Morrison, Henderson, Hawkyard
Goals: Deacon 6
Harlequins (0) 18
Tries: Wells, Randall, Sykes
Goals: Sykes 3
Lesley Vainikolo scored a stunning hat-trick to help his Bradford side claim an eight-try win over Harlequins.
Vainikolo crossed twice in the opening 24 minutes while Joe Vagana and Paul Deacon added two more before the break.
Glenn Morrison and Ian Henderson put the Bulls 34-0 ahead although Jon Wells and Chad Randall grabbed two consolation tries for the visitors.
Vainikolo claimed his hat-trick before Richie Hawkyard marked his home debut with a late try.
Vainikolo, who will switch codes when he joins Gloucester in July, has now scored 17 tries in 16 appearances this season and 147 tries in 148 games during his Bradford career.
Bradford boss Steve McNamara on Vainikolo:
"Les came up with two tries nobody else could have scored.
"We're going to miss him - any side would do - but hopefully we've found a replacement with Tame Tupou coming across next week."
Harlequins coach Brian McDermott:
"There was a call for dissent in the 47th minute which was a little bit of intimidation.
I thought the referee felt intimidated and threw his arm up. If a team's 22-0 down and you can't vent a little bit of frustration - there was nothing abusive said - well, maybe you shouldn't be in that arena.
"But it's not the reason we lost, we lost because we were poor with the ball.
"I thought we probably improved defensively from the Warrington win last week. We didn't miss as many tackles, we were just woeful with the ball in the first half."
Bradford: Platt, St Hilaire, B. Harris, Evans, Vainikolo, I. Harris, Deacon, Vagana, Henderson, Lynch, McKenna, Solomona, Morrison.
Replacements: Hawkyard, James, McAvoy, Burgess.
Harlequins RL: Melling, Wells, Sykes, T. Smith, Clubb, McLinden, Orr, Temata, Randall, Heckenberg, Worrincy, Hopkins, Gafa.
Replacements: Rinaldi, Mills, A. Smith, Burgess.
Referee: Gareth Hewer (Whitehaven)