Mr. Kalas collapsed in the press box at Nationals Stadium in Washington at about 12:30 p.m. and was rushed to George Washington University Medial Center.

The cause of the death was not announced. Today's game against the Nationals will be played, but the team will not visit the White House tomorrow.

"We lost Harry today," David Montgomery, the team president, said. "We lost our voice."

Mr. Kalas, who was found unconsious, missed most of spring training after undergoing undisclosed surgery in Feburary. That surgery was unrelated to the detached retina that sidelined him for part of last season.

Mr. Kalas, who turned 73 on March 26, has broadcast Phillies games since 1971. He was inducted into the Baseball Hall of Fame in 2002 as the recipient of the Ford C. Frick Award. He is entering the final season of a 3-year contract that he signed in December 2006.