Joseph E. Casey, 81, a former Democratic Congressman from Massachusetts and a Washington attorney since 1942, died Tuesday at the Washington Hospital Center. He had cancer.

In 1934, Mr. Casey became the first Democrat elected to Congress from the Third District in Massachusetts. He first ran for Congress in 1924 but was defeated.

He served four terms in Congress unitl 1942, when he was defeated in a bid for a Senate seat by Republican incumbent Sen. Henry Cabot Lodge.

During his years in Congress, Mr. Casey was known as an enthusiastic supporter of the New Deal program. He favored and worked for the Lend-Lease Act of 1941, the maximum-wage-and-hour-law, social security, public housing and other social welfare legislation and rural electrification program.

A successful trial lawyer in Massachusetts before running for Congress, he began practicing law here after his unsuccessful Senate bid and was a partner in the Washington law firm of Casey, Scott and Canfield.

The firm specializes in government contracts and corporate law. He had been semiretired for about two years.

In the early 1950s, Mr. Casey, along with the late Greek shipowner Aristotle Onassis, was one of nine persons indicted in a famous government suit for the return of five surplus tankers bought in 1948 by a firm headed by Mr. Casey. The government suit, which sought the return of the ships was later dropped and Mr. Casey was cleared of any wrongdoing.

Mr. Casey was born in Clinto, Mass. He earned a law degree from Boston University and served as a private in the Army during World War I.

A Washington resident, he was associated with for many years the Boston law firm of Warren, Garfield, Whiteside and Lamson.

Surviors include his wife, the former Constance M. Dudley; three daughters, Jane Kucznski of Washington and Lima, Peru, Constance Casey of San Francisco, and Caroline Casey of Washington; two sons, John, of Charlotttesville, Va., and Joseph, of Eugene, Ore., and seven grandchildren.