Swindon took the lead after only 9 minutes when a Jamie Vincent free kick found Andy Nicholas in the box who headed in to make it 1-0 to Swindon.
Christian Roberts nearly scored a couple of minutes later when his long range shot dipped but hit the bar, and the follow up shot went wide.
After wasting a couple more chances Swindon had a penalty appeal turned down after a foul on Lee Peacock in the box.
Swindon went into the half time break winning 1-0 when it could have been 3-0 if they had taken more of their chances.
In the second half Swindon had less chances, but Michael Pook still missed his shot.
On 71 minutes Darlington made it 1-1 when a cross found Martin Smith who socred from close range.
Overall Swindon should have won, but they just wasted most of their chances. Swindon now have won in the past 3 games and have dropped down to 4th in the table. Swindon travel to North London on Tuesday night to face Barnet in what is now a must win game.