Susan Kelly, 54, of Wheaton was fatally injured Monday at Judgement Farm in Oswego, the Chicago Tribune reported.
The Kendall County Sheriff's Office said Kelly was wearing a helmet but sustained internal head injuries. Kane County Coroner Rob Russell said Kelly hit her head on a concrete footing.
"People fall off their horses quite often but this is the first one [fatality] I've heard of in this area in my 20 years," Sheriff's Deputy Commander Brian Jahp said. "It was one of those weird things, just the way she landed."
Jahp did not know what caused the woman to tumble from the horse's back.
The cause of death was listed preliminarily as blunt force trauma to the head.
"It was just a tragic accident," Russell said.