Atieno ends Robins run
Taiwo Atieno's first-half volley was enough to give Torquay a 1-0 win which ended Swindon's 15-match unbeaten run.
With 34 minutes gone Eunan O'Kane's corner was headed towards goal by defender Chris Robertson and Atieno was on hand to lash the ball high into the net from close range.
At the other end, Robertson made a brilliant block to deflect Matt Ritchie's strike over the goal following a slip by central defender Mark Ellis on the edge of the Torquay penalty area.
Atieno could have doubled his tally at the start of the second half as he raced on to an O'Kane through ball but the striker's shot was brilliantly saved by Robins goalkeeper Wesley Foderingham.
Swindon put Torquay under intense pressure with United goalkeeper Bobby Olejnik making a brilliant stop to deny substitute Ronan Murray in the 76th minute.
Moments later, Murray made a fine goal-line clearance to keep out Ellis' header.
Ritchie looked to have scored with a thundering drive but it was inadvertently blocked on the way to goal by Swindon sub Alan Connell as Torquay held on.