An 11-year-old and a 56-year-old man, both from Pocatello, collided while riding ATVs in Bear Lake County on Monday.
Leonard Chandler and the minor crashed between the Forest Service ranger station and the Cold Springs Campground on Eight Mile Road, said Idaho State Police.
Chandler was driving a 2002 Kawasaki ATV. The minor was driving a 1989 Yamaha.
An ambulance took Chandler to Caribou Memorial Hospital. An air ambulance later took him to Portneuf Medical Center. No information on the boy's condition was available.
Neither driver was wearing a helmet, ISP said.