Paul Sheerin scored a double as St Johnstone leapfrogged Hamilton Accies into second spot in Division One after a first-half goal blitz.
Jason Scotland fired in the opener after a one-two with Steven Milne and Ryan Stevenson bulleted the second into the top corner from a narrow angle.
Sheerin added the third from the spot after Milne was felled before the midfielder slotted in his own second.
Pat Keogh headed in for Accies, but Goran Stanic replied from 35 yards.
St Johnstone: Cuthbert, Mensing, Stanic, Rutkiewicz, James, Stevenson, Henry (McCann 64), Sheerin, Sheridan, Milne (Coyle 84), Scotland (Dobbie 80).
Subs Not Used: Anderson, Paston. Booked: Stevenson.
Goals: Scotland 27, Stevenson 36, Sheerin 44 pen, 45, Stanic 72.
Hamilton: McEwan, Robertson, Fleming, Hodge, Balmer, Neil, Ferguson (Carrigan 56), Wilson (Gilhaney 38), Keogh (Jones 67), MacKenzie, Tunbridge.
Subs Not Used: Thomson, Jellema.
Booked: MacKenzie, Ferguson, Neil.
Goal: Keogh 58.
Ref: A Hunter