Roberts, 52, who was confirmed chief justice of the U.S. Supreme Court in September 2005, remained conscious after tumbling on a dock at his seashore summer home at Port Clyde on Maine's Hupper Island, Supreme Court spokeswoman Kathy Arberg told CNN.
Roberts, the youngest of the court's nine justices suffered only minor scrapes when he fell but was being kept overnight at a hospital to further assess his condition, CNN said.
Roberts has "fully recovered from the incident," and a neurological evaluation "revealed no cause for concern," the Supreme Court said. The incident was described as a "benign idiopathic seizure," CNN said.
It wasn't widely reported, but the chief justice also had a seizure in 1993, CNN said.