Fox, 58, was spending the Broncos' bye week off in North Carolina, where he is still active after having once coached the Carolina Panthers, when the incident occurred.
“Denver Broncos Head Coach John Fox was taken to a Charlotte-area hospital after feeling light-headed while playing golf on Saturday," a statement from the team said.
“He is being held at the hospital for testing and further observation. Our medical staff is currently in contact with Coach Fox, his family and the doctors who are treating him.
“Additional information will be provided as it becomes available.”
The team's executive director of media relations, Patrick Smyth, said Fox may have more tests and may undergo a minor procedure, but would possibly be released from the hospital later Saturday.