Chief Justice William H. Rehnquist was released from a Northern Virginia hospital today after two days of treatment for a fever.

The 80-year-old chief justice, who has been battling thyroid cancer, went home following his discharge from the Virginia Hospital Center in Arlington, where he underwent tests and observation, Supreme Court spokeswoman Kathy Arberg said.

No other information on Rehnquist's condition was immediately released, and he has refused to comment on any retirement plans.

Ernest Mazzaferri, professor of medicine at the University of Florida and president-elect of the American Thyroid Association, said Rehnquist's departure from the hospital was "good news," Washington Post staff writer Charles Lane reported.

Mazzaferri said that when he heard the chief justice had a fever, he suspected pneumonia, which often afflicts patients such as Rehnquist who have had surgery to insert a tube into the throat to permit breathing.

While cautioning that he does not have direct information on Rehnquist's condition, Mazzaferri said pneumonia still cannot be ruled out and that treatment for it could be continued at home.

Although Rehnquist was widely expected to retire after the Supreme Court ended its session last month, it was Justice Sandra Day O'Connor who issued a surprise retirement announcement, giving President Bush his first opportunity to choose a Supreme Court justice. O'Connor, 75, announced July 1 that she would retire upon the Senate's confirmation of her successor.

Rehnquist, who has served on the Supreme Court for 33 years, was taken to the hospital by ambulance Tuesday night after he complained of a fever, a common ailment among cancer patients. The chief justice has undergone chemotherapy, radiation and a tracheostomy during his treatment for thyroid cancer.

The hospitalization was disclosed only after Rehnquist failed to show up at his Supreme Court office Wednesday morning and reporters saw court police retrieve his cane and several items of clothing from his home. In response to media inquiries, Arberg then confirmed that the chief justice had been taken to the hospital.

Despite intense speculation about the prospect of a second vacancy on the Supreme Court, the ailing jurist has remained mum in public, showing no sign of any intention to leave. When reporters waiting for him outside his house asked him last week whether he was going to retire, he replied, "That's for me to know and you to find out."

Even the White House apparently has been kept in the dark, relying on media reports for information on Rehnquist's health. White House spokesman Scott McClellan told reporters that Bush was informed of the hospitalization Wednesday afternoon on the basis of news bulletins.

Bush reportedly wants to announce a nominee to replace O'Connor before he leaves for vacation on July 28.