Hamilton's poor record at McDiarmid Park continued on Saturday as Johnstone ran out of comfortable winners in Perth.
For St Johnstone it's an impressive five games unbeaten, while goalkeeper Zander Clark set up a new club shut-out record.
For Hamilton though it's back to the drawing board, especially with Celtic up next in a fortnight.
First-half goals from Murray Davidson and Drey Wright had Saints on easy street by the interval, and they simply never looked back.
Mickey Miller, Tom Taiwo, James Keatings and Fredrik Brustad dropping out in favor of Darian MacKinnon, Dougie Imrie, Steven Boyd and Mason Bloomfield.
Tommy Wright made two changes from the side that beat Hibs last week, as Davidson and David Wotherspoon came in for Ross Callachan and Tristan Nydam.
Liam Craig has made a great effort to make it over the top right corner of the box.
In five minutes a decent cross from the left reached Wright in plenty of space, but he sent his angled drive well out of the left post.
Liam Craig's ninth-minute free kick caused havoc for the Hamilton defense and there was a claim.
Saints used to do a well-rehearsed move in Liam Craig playing the ball back to Matthew Kennedy, but his powerful shot was well blocked.
Gordon on the right, his cutback was fumbled by Gary Woods into the path of Davidson, who smashed it into the net.
Accents took until the 32nd minute before they had anything approaching, as Aaron McGowan's powerful shot was blocked.
Saints scored their second goal in 36 minutes in bizarre fashion when Wright's cross shot straight from the woods and into the net.
Tony Watt's through ball released Matty Kennedy and he dinked the ball outrushing Woods and into the net.
Saints tried their luck again at 68 minutes with a powerful Wotherspoon free kick from the left, but Woods parried and finally cleared it.
A minute later Ziggy Gordon's headed clearance fell to Kennedy and he lashes off the crossbar from 30 yards.
But Saints added a fourth in 74 minutes when Chris Kane Mugged Delphine Tshiembe on the right and his path was turned into the path of Wotherspoon to smash into the net.
Sam Kelly, but his shot was deflected over. From Imrie's corner Bingham's shot hit the top of the crossbar.
ST JOHNSTONE: Clark, Foster, Shaughnessy, Kerr, Tanser, Wright, Davidson, Craig (Nydam, 80), Wotherspoon, Kennedy (McMillan, 77), Watt (Kane, 63).
Subs (not used): Hurst (GK), Scougall, Gordon, Callaghan.
Bookings: Kennedy (62)
HAMILTON: Woods, McGowan, Kilgallon, Tshiembe, Gordon, Martin (McMann, 61), MacKinnon, Boyd (Kelly, 46), Imrie, Bingham, Bloomfield (Brustad, 72).
Subs (not used): Marsden (GK), Taiwo, Penny, L. Smith.
Bookings: Imrie (18), McGowan (39), Martin (51), MacKinnon (74)
Referee: Steven McLean.