John Maktos, 74, an internationally-known lawyer who held a number of top positions in the State Department, died Saturday at George Washington University Hospital after a heart attack.

He had assisted in the preparation of the United Nations Charter and participated in the 1945 San Francisco conference that created the United Nations.

Mr. Maktos was chief of the legal division of the State Department's office of United Nations affairs from 1945 to 1948. He then was assistant legal adviser in charge of affairs relating to all international organizations.

From 1951 until his retirement from the State Department in 1962, he was assistant legal adviser in charge of Near Eastern, South Asian and African affairs.

A graduate of Harvard University, where he also received his law degrees, Mrs. Maktos took postgraduate work at Oxford University and the University of Paris.

He entered the State Department in 1929 as assistant to the solicitor in 1932, he was an attorney for the U.S. before the American-Turkish Claims Commission, preparing over 1,000 claims of Americans against Turkey. He also was in charge of claims of this country against Japan and other Asian countries.

In World II, Mr. Maktos was chairman of the Interdepartmental Visa Review Commitee, composed of representatives of the State, Justice, War and Navy Departments.

He also was general counsel of the American-Mexican Claims Commission in the latter part of the war.

Mr. Maktos had represented this country at many international conferences. In 1948, he was chairman of the U.N. Committee on Genocide. In the early 1950, he had served as U.S. delegate to the U.N. Committee on International Criminal Jurisdiction and the Committee on Aggression.

He was a former professor at Columbus Unversity Law School, which became part of Catholic Unversity, and lectured at Cornell, George Washington and Yale Law Schools and the Washington College of Law.

A former associate editor of the Federal Bar Association Journal, he was the author of "Federal Legal Functions" and "Comparative" Conflict of Laws" and contributed to numerous legal periodicals.

After retiring from the State Department, he and a nephew, P. D. Maktos, formed a private law practice in Washington. He is also became a member of the National Panel of arbitrators of the American Arbitration Association.

Mr. Maktos was a member of the American and Federal Bar Associations and the American Society of International Law. He belonged to the Cosmos Club and the International Club of Washington.

He held a number of awards and decorations, including the Commander of the Royal Order of George I of Greece and the Ecumenical Patriarch of the Order of Knights of Saint Andrew.

He was a life member of the British association of Friends of St. George's Chapel and Descendants of the Knights of the Garter and a charter member of the British Association of Descendants of King William the Conqueror.

He is survived by his wife, Bernice Virginia Maktos, of the home in Washington.