Supreme Court Justice William J. Brennan is expected to "respond very well"to treatment for pneumonia and may miss only one session, a court spokeswoman said.

Brennan, at 82 the oldest member of the court, was taken to the Bethesda Naval Medical Center in suburban Maryland on Thursday after visiting a doctor at the U.S. Capitol, court spokeswoman Toni House said."Justice Brennan was admitted with pneumonia," she said. "He is being treated with antibiotics, and doctors expect him to respond very well."

House added, "His illness is not expected to affect his work except for the Monday, Dec. 12, session."

The court is scheduled to begin a four-week recess after issuing orders and possibly announcing decisions Monday.

House declined to answer other questions concerning the justice's health or his hospitalization.

On Thursday night, court spokeswoman Kathy Arberg said Brennan was "in good condition and resting comfortably."

A spokesman for the medical center would confirm that Brennan is a patient there but declined to offer any information about his condition.

A court employee who spoke only on the condition of anonymity said Brennan left his court office in the early afternoon, suffering from a fever and the chills.

Brennan participated in the court's oral arguments Wednesday, and reportedly has enjoyed good health recently.

His last hospitalization occurred in August 1987 when he checked into the Mayo Clinic in Rochester, Minn., for tests on his prostate gland. Tests revealed he did not have cancer.

Brennan, appointed by President Dwight D. Eisenhower in 1956, is its oldest and most senior member of the court.

For three decades the court's leading liberal light, Brennan is now one of three liberal, octogenarian justices. Thurgood Marshall and Harry A. Blackmun are 80.

By comparison, the average age of the court's conservative justices is about 60.