Martin Joseph Ward Sr., 64, the president of the 380,000-member United Association of Plumbers and Pipe Fitters (AFL-CIO), died Saturday at a hospital in Easton, Md., following a heart attack.

Mr. Ward, who lived in Bethesda and who was on a fishing trip when he was stricken, was a member of the AFL-CIO's executive council, the ruling body of the organization, and headed the council's international affairs committee.

He first was elected head of the plumbers union in August 1971. He was in the second year of his third term when he died.

"He was an outstanding leader for his union and for the federation," AFL-CIO President Lane Kirkland said of Mr. Ward. "His death is a great tragedy, coming especially at a time when the federation had increased its international activities."

A spokesman for the AFL-CIO's Building and Construction Trades Department said the executive board of the United Association of Journeymen and Apprentices of the Plumbers and Pipe Fitting Industry of the United States and Canada would meet in the next several days to elect a successor to complete Mr. Ward's term.

Robert A. Georgine, president of the Building and Construction Trades Department, which is composed of 15 building and construction trade unions, called Mr. Ward "an outstanding trade unionist and a pillar of our department."

Mr. Ward traveled widely as a representative of the American trade union movement. He played a significant role in negotiations that led the AFL-CIO earlier this year to rejoin the International Confederation of Free Trade Unions.

Since 1974, Mr. Ward also had served as U.S. labor's representative at the conferences of the International Labor Organization in Geneva, Switzerland.

The son of a plumber, Mr. Ward was born in Chicago. He attended the Armour Institute. He started his apprenticeship in 1937 and became a journeyman pipe fitter in 1942. During World War II, he was in the Navy.

In 1948, he was named business representative of pipe fitters Local 597 in Chicago. He became assistant business manager in 1950 and business manager two years later.

While he was an officer in his local union, Mr. Ward also served as vice president of the Cook County Building Trades Council and secretary of the Illinois Building Trades Association. He was a member of the Chicago Joint Conference for the Settlement of Jurisdictional Disputes.

In 1958, Mr. Ward was elected assistant general secretary-treasurer of the plumbers international union and moved to its headquarters in Washington. In 1966, he was elected general secretary.

He was a member of the parish of St. Bartholomew's Catholic Church in Bethesda.

Survivors include his wife, Winifred, of Bethesda; seven sons, Martin J. Jr., of College, Alaska, Patrick T., of Wheaton, Terrence R., of Chicago, Kevin R., of Rockville, Philip J., of Tucson, and Brian D. and Dennis J., both of Bethesda; two sisters, Katherine Dorgan, of Tucson, and Mary Sanaghan, of Chicago; a brother, John, of West Long Beach, N.J., and nine grandchildren.