In the fifteenth minute Nathan Lowndes got on the end of a cross from Gerry McMahon, but his header lacked power, and Jim Leighton saved easily.
St Johnstone broke the deadlock after 17 minutes through Nathan Lowndes.
Half - time, one nil to Saints.
The pattern of the second half followed the first, with St Johnstone with the bulk of possesion. Gerry McMahon incresed their lead after 66 minutes.
Aberdeen tried to get something back, but they couldn't find a way past the Saints defence.
Final score - Aberdeen 0 St Johnstone 2