After falling behind, goals from Peter Noble, Arthur Horsfield and John Trollope see Swindon through to the FA Cup Quarter Finals on the County Ground quagmire.
England cricketer Ian Botham is in the stands to watch his side claim a point in a drab draw at a rain-soaked County Ground.
Christian Roberts' late penalty rescues a point for ten man Swindon, after striker Rory Fallon is shown red.
The Town come from behind for a potentially crucial win - the victory putting them three points from safety with three to play.
Simon Cox nets his second hat-trick of the season - but just as for his first, it's only good enough for a 3-3 draw.
League leaders Scunthorpe take a two goal half-time lead - but after they have two players sent off early in the second half, Swindon play it superbly well, netting four times to win 4-2.
Aden Flint's first half red card puts Town on the back foot, and the Iron grab a second half equaliser.
With the home side needing victory to have any chance of staying in the division, James Collins appears to kill off any Scunthorpe hopes with a goal seven minutes from time - and though the home side score three times in a crazy last three minutes, results elsewhere confirm their relegation.
Swindon get the season off to a winning start with a slick opening day victory over Scunthorpe.
Michael Smith gives Swindon the lead on the stroke of half-time, but Scunthorpe come roaring back in the second half to secure a comfortable win.
The Town are thumped at Scunthorpe for the second season in succession - the defeat taking them into the relegation zone.
Rohan Ince's superb late strike is in vain - Scunthorpe's victory confirming the Town's relegation to League Two, and leaving the fans calling for the chairman to resign.
Swindon start the season in style - two impressive counter-attacking goals giving them an opening day victory at Scunthorpe.
Having not scored since New Year's Day, top scorer Eoin Doyle nets his 24th and 25th of the season in a straightforward win, to put the Town three points clear.