Chief Justice Roberts was released from a hospital yesterday after suffering a seizure yesterday near his summer home in Maine. Justice Roberts, 52, smiled and waved as he walked to a vehicle that took him away from the hospital in Rockport, Maine. “He is going to continue his vacation,” Supreme Court spokeswoman Kathy Arberg said in Washington. Earlier yesterday, Justice Roberts got a phone call at the hospital from President Bush.

“The chief justice assured him that he was doing fine,” presidential spokesman Tony Snow told reporters. Mr. Snow said the White House was aware Justice Roberts suffered a similar seizure 14 years ago and promised to investigate further about the seriousness of the chief justice’s condition. “Chief Justice Roberts had made known his history of seizure to those who were doing vetting” when Mr. Bush named him to the court in 2005, Mr. Snow said.

Ms. Arberg said Justice Roberts suffered the seizure and fell on a dock near his summer home in Port Clyde, Maine. He had just stepped off a boat after running errands, and he was taken by ambulance to Penobscot Bay Medical Center in Rockport, she said. Doctors found “no cause for concern” after conducting a neurological exam, Ms. Arberg said. Justice Roberts suffered a “benign idiopathic seizure,” she said. That means the seizure is of unknown cause and isn’t considered harmful.

Justice Roberts stayed overnight at the hospital as a precaution, Ms. Arberg said. “The chief justice is fully recovered from the incident,” in which he suffered minor scrapes, she said yesterday.

Suffering two unprovoked seizures is by definition considered epilepsy, though when they occur 14 years apart “that’s about as mild as it could get,” said Dr. Frank Gilliam, director of the epilepsy center at Columbia University Medical Center in New York. He isn’t involved in treating Justice Roberts.

“He’ll need to discuss with his neurologist whether starting a medication is even warranted” to ward off future occurrences, Dr. Gilliam said in a telephone interview yesterday.

The chances of suffering side effects from such drugs are less than 30% to 40%, the doctor said. The most common side effects of anti-seizure medication are fatigue or problems with concentration, the doctor said, though he said several medicines introduced in the last several years have minimal side effects.

“It’s very unlikely that either the seizure or medication treatment would have any adverse impact on his ability to function as a judge,” Dr. Gilliam said. He will also be told not to drive for now, the doctor said. Most states require drivers to be free of seizures for at least six months, Dr. Gilliam said.

Paul Garcia, a neurology professor at the University of California, San Francisco, said such seizures are relatively common. About 10% of Americans have a seizure at least once in their lifetimes, and about half of those are unexplained.

People often have seizures without any known long-term effects, Mr. Garcia said in a telephone interview yesterday. The most obvious risk of an unexpected seizure like the one Justice Roberts had is that it may lead to an injury, either from falling or some other type of accident, he said.