Saulius Mikoliunas salvaged a point for Hearts with a late strike in a dour encounter in blustery conditions.
Saints keeper Chris Smith denied Hearts early on with superb stops to deny Andrew Driver and Christos Karipidis.
Jim Hamilton broke the stalemate against his former club after 58 minutes with a left-foot volley from Craig Dargo's clever lay-off.
Andy Dorman then hit the post but Mikoliunas' solo effort four minutes from time denied Saints a deserved win.
Hearts were without injured trio Christian Nade, Laryea Kingston and Ibrahim Tall and Jamie Mole was brought in for his first SPL start.
St Mirren had no fresh injuries with in-form Andy Dorman retaining his place.
The hosts opened brightly, taking the game to the visitors with some neat inter-linking play between Franco Miranda and Dargo.
But they were unable to threaten Steve Banks in the Hearts goal.
Ruben Palazuelos tried his luck for Hearts in the sixth minute, but his driven effort from 30 yards flew harmlessly past Smith's right-hand post.
After 12 minutes, Ian Maxwell connected with a low corner and from six yards out hit a shot goalwards - but Christophe Berra blocked.
The home team claimed a hand was used, but referee Willie Cullom turned down the half-hearted penalty appeal.
In the 27th minute veteran defender Andy Millen replaced injured John Potter.
The unfortunate Saints player was stretchered off after receiving an accidental foot in the face from Mikoliunas.
Two brave point-blank saves from Smith kept the scores even after 35 minutes.
The home keeper first denied Andrew Driver and then from the resulting corner a Karipidis header.
A rasping shot from Dorman had the home support on their feet, but his long-range effort never troubled Banks as it screamed over the bar.
Straight after the restart, Hearts made their intentions clear when Callum Elliott came within inches of putting the visitors ahead.
His powerful half-volley was struck convincingly, but Smith in the St Mirren goal was alert and managed to get a fingertip to the ball.
Hearts again threatened with a pinpoint pass by Palazuelous towards the onrushing Elliott, but his shot from 16 yards was weak and wide of the target.
In the 59th minute, Hamilton blasted St Mirren into the lead with a ferocious strike from seven yards after a clever Dargo knock-down.
St Mirren nearly doubled their lead 10 minutes later but Dorman's shot cannoned off the post with Banks beaten.
Hearts rescued a point with only four minutes remaining when Mikoliunas hit an unstoppable shot from 18 yards.
Then Dorman squandered two great chances to pinch victory for St Mirren.
St Mirren: Smith, Barron, van Zanten, Potter (Millen 29), Maxwell, Mason, Dorman, McGinn (Murray 77), Miranda, Hamilton, Dargo (Mehmet 83). Subs Not Used: Howard, Kean, Corcoran, Docherty.
Booked: McGinn, Miranda, Smith.
Goals: Hamilton 58.
Hearts: Banks, Neilson, Berra, Palazuelos, Wallace, Mikoliunas, Jonsson (Stewart 58), Karipidis, Driver (Cesnauskis 39), Elliot, Mole (Beniusis 67). Subs Not Used: Basso, Zaliukas, Ksanavicius, Thomson.
Goals: Mikoliunas 86.
Att: 4,557
Ref: W Collum (Scotland)
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