A black, green and gold side without the majority of their regular matchday 23 always had their work cut out against an outfit saturated with international caps.
The Barbarians had motored into a 29-0 lead by the break, with 72-cap Wallaby fly-half James O'Connor pulling the strings.
The home fans did finally have something to shout about at the start of the second half as George Hendy went over.
And Toby Thame was also able to etch his name on the scoresheet before the end as Saints produced a more effective second period.
It was a second defeat in as many pre-season matches ahead of the start of the Premiership Rugby Cup campaign at Ealing Trailfinders next Sunday.
But Saints will continue to add in more experienced first-team players to bolster their cup bid.
The black, green and gold had started the game against the Barbarians on the front foot, threatening the line, but it was the away side who scored first as they landed a sucker punch in the fifth minute.
A slick move, which drew applause from the home fans, was finished off by skipper Ryan Lonergan, who also added the conversion with ease.
Seru Uru then had to do some good work at the other end, bundling Hendy into touch with the line in sight.
There was a lot of huff and puff before the Barbarians added to their tally, using a quick tap penalty to get numbers out wide, where full-back Tom Wright scored.
The conversion came back off the left post to leave the gap at 12 points, but it was soon 19 as James Grayson's pass went loose and Dylan Pietsch picked up to sprint home for the try.
Lonergan converted with ease before Jake Garside helped to prevent more damage, flying over and flooring Uru, who couldn't make any further ground despite a huge size advantage.
More good defensive work was done by guest player Theo Vukasinovic, who held up powerful flanker Lachlan Swinton over the line.
But the Barbarians had their fourth try moments later as some lovely combination play between James O'Connor and Wright opened the door for Hunter Paisami to go close before Caderyn Neville picked up to score.
The conversion was missed but the Barbarians had another try after pouncing on the counter-attack.
Tom Cruse dropped the ball just inside the away half and the men in black and white moved quickly before Filipo Daugunu showed his sharpness to score.
Lonergan missed the conversion but the gap was now 29 points, and Saints were unable to trouble the scoreboard before the break.
However, the black, green and gold were fastest out of the blocks at the start of the second period, with talented young scrum-half Archie McParland helping to lift the tempo.
And after a period of pressure in the Barbarians 22, Hendy found a nice line to score his side's first try of the game and his third in two pre-season matches.
Grayson sent the conversion wide and the Barbarians hit back with a fine score, Lonergan's excellently executed chip picked up by the classy Wright, who finished with aplomb.
O'Connor sent the conversion just wide but he soon made amends with a much easier effort after Harry Johnson-Holmes used his power to score.
Saints responded well and after Garside's pass went loose, Hendy picked up and looped a nice pass in the direction of Toby Thame, who scored.
Grayson converted nicely from out wide but the Barbarians again issued a riposte, breaking well once again to allow Nicholas McCurran to grab a try.
Paisami converted and Saints continued to ring the changes, with the impressive Garside given a huge ovation as he was replaced with 10 minutes to go.
The closing stages of the game were understandably scrappy, with the Barbarians seeing it out comfortably.
Saints: Hendy; Glister (Daniel 59), Seabrook (Thame 52), Litchfield (Baker 62), Garside (Arden 71); Grayson, Braley (McParland 40); Waller (Millar Mills 40 (Smyth 78)), Cruse (c) (Wright 62), Hill (Prowse 40); Vukasinovic, Irvine (Sylvester 40); Scott-Young (Lavin 52), Pollock (Gradwick-Light 70), Moore-Aiono.
Barbarians: Wright (Yamanaka 52); Anderson, Daugunu (McCurran 52), Paisami, Pietsch; O'Connor, R Longeran (c) (Shingeno 52); Lambert (Kobayashi 52), L Lonergan (Nakamura 52), Talakai (Johnson-Holmes 52); Helu, Neville; Swinton, Uru, Makisi (Wilson 40).
Referee: Ian Tempest