Barnsley are in trouble at the wrong end of the Sky Bet League One table after they were sunk by a clinical second-half show from Swindon.
The Robins bossed the final half-hour of the Oakwell clash as they scored three times and condemned the hosts to a fifth league game without a win.
It had been a dismal goalless first period, with Jean-Yves M’voto missing the Reds’ best chance when he volleyed over from 12 yards.
After the restart Devante Cole should have done better when he fired straight at ‘keeper Wes Foderingham, while at the other end Michael Smith was denied by Ross Turnbull’s brave save.
The breakthrough finally came just before the hour mark when Nathan Byrne skipped past a couple of feeble challenges from the Reds defence before slotting comfortably past Turnbull into the corner.
Sub Andy Williams crashed a shot straight at Turnbull as the Robins threatened to turn the screw.
Dale Jennings came on for the Reds and he nearly made a perfect impact.
The pacy wide-man expertly tee’d up Kane Hemmings, but his shot was blocked.
Back came Swindon, with Williams trying a cheeky chip which Turnbull had to be at full stretch to tip over the crossbar.
Two goals inside 60 seconds sealed the Reds’ fate.
In the 83rd minute sub Jake Reeves slotted home following Byrne’s cross, while Williams then converted a similar assist from Smith.
Barnsley (4-3-3): Turnbull; Bree, M’voto, Nyatanga, Dudgeon; Bailey, Cranie, Hourihane; Hemmings, Cole, Winnall.Subs: Davies, Brown, Berry, Treacy, Jennings, Noble-Lazarus, Lita.
Swindon (3-5-2): Foderingham; Turnbull, N Thompson, Stephens; Byrne, Kasim, Luongo, L Thompson, Bell; Obika, M Smith.Subs: Belford, Williams, Reeves, Barker, Barthram, Waldon. Rodgers.
Referee: Chris Kavanagh (Manchester).