The 33-year-old Warwickshire player was one of their several absentees from the recent tour of India after failing to recover as quickly as anticipated from hip surgery.
England and Wales chief medical officer Peter Gregory, said: "In light of the lack of progress with Ashley's rehabilitation from hip surgery, his surgeon recently recommended an opinion was sought from a hernia specialist.
"The view of this specialist, who was consulted last week, was that Ashley has developed a defect known as a Gilmore's Groin - which could account for the pain he suffers after he runs.
"Ashley will undergo surgical repair in the near future. It is hoped that this will enable him to return to cricket later this season."
That hip injury dated back to the start of last summer and Giles missed two Tests against Bangladesh before the 2005 Ashes, and was also forced to leave the pre-Christmas tour of Pakistan.