Rep. Joseph P. Addabbo, 61, a New York Democrat who as chairman of the defense subcommittee of the House Appropriations Committee built a reputation as an articulate and forceful opponent of what he considered excessive military spending, died late Thursday night at Walter Reed Army Medical Center. He had cancer and recently had suffered a heart attack.

Mr. Addabbo, who had been in a coma since collapsing March 6, represented a district in Queens. He served for 25 years in the House of Representatives and since 1979 had been chairman of the defense appropriations subcommittee, the panel that acts on requests for all military spending. In that role he was often critical of high military officers who, he said, frequently shared with civilian bureaucrats a penchant for empire building and a narrowness of vision.

Despite his reputation as a critic of military spending, Mr. Addabbo always insisted he supported a strong defense policy. "But I don't take the Pentagon at their word," he once said. "I don't like the attitude of some members, 'Well, let's give them $20 million to play around with this year. Let's give them $40 million next year.' Three years later, the weapon doesn't work, and there's $100 million down the drain."

But Mr. Addabbo often found himself in a minority position on his own committee, most of whose members tended to have more hawkish views than he. More often than not he was on the losing side of defense-spending controversies.

He tried in 1982 to block funding for the MX missile but lost, both in his own subcommittee and in the full Appropriations Committee. He prevailed when he took his case to the floor of the House, although the House later reversed its position and work began on the missile.

In 1973 Mr. Addabbo sponsored the first antiwar resolution ever to pass the House of Representatives -- the cutting off of funds for the bombing of Cambodia. He had supported the war in Southeast Asia during the Johnson administration and in the early years of the Nixon presidency but he subsequently changed his mind. He also opposed the B1 bomber and other major weapons systems.

In 1984 he castigated the Defense Department for what he called "a complete breakdown of control over millions of dollars." This followed a report that accused the military of scrapping valuable equipment, then turning around and paying higher prices to buy identical items.

President Reagan called Mr. Addabbo "one of the leading players in the development of American military policy." He said the congressman was "widely respected for his knowledge of defense issues even by those who disagreed with him. His genial style was in keeping with the best traditions of American politics."

House Speaker Thomas O'Neill said Mr. Addabbo "worked diligently to ensure that America's defense was strong, efficient and effective. He demanded quality for each defense dollar."

New York Gov. Mario Cuomo called him a "great man whose commitment to integrity and excellence has improved the quality of life for all New Yorkers."

Mayor Edward Koch of New York ordered flags on city buildings to be flown at half staff until after Mr. Addabbo's funeral. The congressman, Koch said, "always strove to ensure that people of every race, religion and ethnic origin had a fair hearing and full representation in the halls of the Capitol."

A native of New York City, Mr. Addabbo graduated from the City College of New York and St. John's University Law School. He practiced law in Queens, participated in civic and community organizations, and headed Italian-American committees for various candidates.

But he never ran for public office until 1960, when the incumbent Republican representative from his district retired. With the help of John F. Kennedy's drawing power among Catholic voters, Mr. Addabbo won with 53.5 percent of the vote.

In the ensuing years the district changed from a predominantly middle class Catholic suburb to an area more closely resembling the inner city, with a population that was 65 percent black and Hispanic by the 1984 election.

During that time Mr. Addabbo established a record of steering defense contracts to Long Island-based industries and listening to constituent problems and complaints. He voted in favor of federal aid to education and the elderly, in favor of civil rights, and against measures to limit rights to abortion or allow prayer in public schools.

He won most bids for reelection handily, and in the campaigns of 1974 to 1982 had the Republican as well as the Democratic nomination. In 1984 he was challenged in the Democratic primary by Simeon Golar, a black real estate developer, who asked the voters to oust Mr. Addabbo on the argument that since the district had a black majority it should have a black representative. Mr. Addabbo won with 68 percent of the vote.

He is survived by his wife, Grace, and three children, Dominic, Dina and Joseph.