The Heineken Cup champions were missing 11 internationals and a further seven players to injury but it was nonetheless a rousing statement intent from the a side, considered Wales' underachievers, in Simon Easterby's first match in charge.
Wingers George North and Andy Fenby both crossed twice while centre Scott Williams and replacement Kieran Murphy both got in on the act.
But it was full-back Liam Williams who stole the show with his devastating lines cutting the Leinster defence to ribbons resulting in a try and the man-of-the-match award.
And while Williams, who won his previous cap against the Barbarians, has played all over the backline, he feels that it is in the No.15 shirt he can cause the most damage.
However the 21-year-old was quick to apportion as much praise to the Scarlets pack as their talent-filled backline.
"We knew Leinster were going to come with a big pack but ours matched it and more I guess.
"That was probably the best performance by myself and the squad since I have been here.
"We have got a really talented back-line - I thought Gareth Maule was exceptional and we scored some great tries
"Full-back is my preferred position and that was my kind of game."