The young spinner, who made his Test debut at Trent Bridge in the Ashes series opener, hit a record 98 for a No. 11 batsman on debut. However, Australia lost the Test by 14 runs. The 19-year-old also featured in the second Test at Lord's.
The fifth and final Ashes Test begins today at The Oval. Agar left for Australia on Tuesday (August 20). England have already won the series with a 3-0 lead.
Cricket Australia (CA) advises that spinner Ashton Agar will return to Australia this evening. Agar has been unwell for the past week and subsequently a decision has been made to allow him to return early to Australia, a statement from CA said.
Australian Cricket Team doctor Dr Peter Brukner said: "Ashton has had a mild viral illness for the past week and needs some time to rest and recuperate. It has been a long tour and while he has handled the pressure extremely well, we thought it would be a good idea for him to get home as soon possible to have a short break before preparing for the domestic season."