Frederick A. Muhlenberg, 92, a former Republican congressman from Pennsylvania and a much-decorated veteran of World War I, died Saturday at a Reading, Pa., hospital after a heart attack.

Mr. Muhlenberg served in Congress from 1946 to 1948. He was the first Republican elected from Pennsylvania's Berks County after it became a separate congressional district in 1932.

The sixth generation of his family to serve in Congress, he was a direct descendent of Frederick Augustus Muhlenberg, who served as the first Speaker of the House of Representatives.

His other prominent forebears include Heinrich Melchior Muhlenberg, a German clergyman who settled in Pennsylvania in 1742 and became leader of all Lutherans in the colonies, and Heinrich's eldest son, Gen. John Peter Gabriel Muhlenberg, also a Lutheran clergyman, who dramatically discarded his clerical robes to serve on Gen. Washington's staff and who later served in the Senate.

Before the Civil War, three other of Mr. Muhlenberg's ancestors were elected to the House of Representatives.

A native of Reading, Mr. Muhlenberg earned bachelor's and master's degrees from Gettysburg College in Pennsylvania. He also earned a bachelor's degree in architecture from the University of Pennsylvania.

He founded the Muhlenberg-Greene architectural firm in Reading and served as senior partner until his retirement about two years ago. Since then, he was serving as a consultant to the firm.

During World War I, Mr. Muhlenberg was an infantry captain in the 79th Division. His military decorations include the Distinguished Service Cross, the Legion of Merit, Two Purple Hearts, the Croix de Guerre and the French Legion of Honor.

Mr. Muhlenberg also served five years of active duty with the Army Engineers during World War II.

His wife, the former Elizabeth S. Young, died in 1967.

Survivors include two daughters, Caroline M. Hufford of Charleston, W.Va., and McLean, and Frederica M. Bunge of Washington; a son, John D. S., of Vienna, Va. and eight grandsons.