George Lewis Warren, 91, a retired authority on refugees and migration with the State Department and an adviser to U.S. delegates to the United Nations, died of congestive heart failure Wednesday at the Wisconsin Avenue Nursing Home, where he had resided for the last five years.

He was a consultant to the President's Advisory Commission on Refugees and Displaced Persons in the State Department from 1943 until retiring in 1968. Form 1944 to 1946, he was a member of the U.S. delegations to the United Nations Relief and Rehabilitation Administration. In 1945 and 1946, he was a U.S. representative to the Intergovernmental Commission on Refugees in Paris and London. From 1948 to 1952, he was a delegate to the Executive Committee, International Refugee Organization, in Lausanne, Switzerland. In 1951, he was a delegate to the Conference of Plenipotentiaries on the Status of Refugees and Stateless Persons in Genevea, Switzerland.

Mr. Warren also was the U.S. representative to the Council Intergovernmental Committee for European Migration from 1952 to 1966. He had been an adviser to the U.S. delegate to the U.N. General Assembly in New York several times. He was on the Committee of Experts to Revise the Statute of Office of the U.N. High Commissioner for Refugees in 1959.

He was born in Wellesley, Mass., and graduated fropm Harvard University. He became director of the International Migration Service in 1928, serving in Geneva and New York until 1938. He then was adviser to the League of Nations Temporary Committee on Indigent Aliens in Geneva, the Evian Conference on Refugees in Switzerland, the Conference of American States Members, International Labor Organization, in Havana, and in 1943, the Anglo-American Conference on Refugees in Bermuda.

Mr. Warren's awards included honors from Czechoslovakia, the Dominican Republic, the Netherlands, Belgium and Italy. He was made Knight Commander, Order of St. Gregory the Great, by Pope Pius XII. He received the State Department's Superior Service Award.

For many years he had written annual articles on refugees for the Encyclopedia Britannica and the New International Year Book. He was a member of the Cosmos Club.

His wife, the former Mary Gertrude Cuniff, died in 1966. A daughter, Helen Elizabeth Langley, died last year.

Survivors include another daughter, Mary Rogers of Barcelona, N.Y.; a son, George Lewis Jr. of Washington and Geneva, 11 grandchildren and two great-grandchildren.