Leonard W. Hall, 78, the chairman of the Republican National Committee when President Dwight D. Eisenhowed ran successfully for reelection in 1956, died Saturday in a hospital in Glen Cove, N.Y. The cause of death was not disclosed, but Mr. Hall had a stroke last April.

A highly respected manager of the political campaigns of others Mr. Hall also was a successful candidate in his own right. He served five years in the New York State Assembly and seven terms in the U.S. House of Representatives. He also was elected sheriff of Nassau County, where he was born on Long Island, and as the country's surrogate judge, the judicial official who is in charge of probate and related matters.

Mr. Hall was chairman of the Republican National Committe from early in 1953 until 1957. He was credited with organizing the campaign in which President Eisenhower defeated Adlai E. Stevenson, the Democratic nominee, for the presidency a second time. Eisenhower's margin of victory was 9.5 million votes.

Eisenhower suffered a heart attack in 1955 and his plans for his political future were uncertain. Mr. Hall was among those who persuaded him to become a candidate again. Mr. Hall's skillful use of television was a factor in the lopsided victory.

When Mr. Hall resigned as GOP chairman, The Washington Post said in an editorial that he was leaving "the political stage with plaudits for one of the most remarkableperformances in the annals of his party. . . . Mr. Hall's management of the presidential campaign commands the same kind of respect that was accorded to Democratic National Chairman James A. Farley in his day. Opponents could rail at his tactics and still be charmed by his bullish amiability."

Mr. Hall, who was an attorney in Nassay County in private life, managed Richard M. Nixon's unsuccessful campaign against President John F. Kennedy in 1960. Kennedy won by a narrow margin.

By 1968, when Nixon ran successfully for the presidency, Mr. Hall was supporter of Govs, Goerge Romney of Michigan and Nelson A. Rockefeler of New York, two unsuccessful candidates for the Republican nomination that year.

Leonard Wood Hall was born at Oyster Bay, N.Y., on Oct. 2, 1900. His parents were Franklyn H. and Mary A. Hall. His father was the coachman at the Oyster Bay estate of Theodore Roosevelt, then the vice president. When Roosevelt became president Franklyn Hall went to Washington with him and became the chief White House messenger.

The boy was named after Gen. Leonard Wood, a hero of the Spanish-American War. His godmother was Ethel Roosevelt Derby, a daughter of Theodore Roosevelt.

His father died in 1915. The young Mr. Hall moved to Washington the following year and went through Georgetown University Law School at night while working for the Potamac Electric Power Co. He graduated in 1920 and then went to work in a New York law office.

He was elected to the New York State Assembly in 1927, but served there only a year. He returned to Nassau County, where he was elected sheriff. He served in the legislature again from 1934 to 1938, when he was elected to Congress.

He resigned his seat in 1952 to run for surrogate judge of Nassau County, a job that paid $30,000 a year compared to the $12,000 a year that Congressmen made at that time. He was elected by a wide margin even though he was a full-time member of President Eisenhower's election staff.

He reigned the judgeship to become GOP national chairman, a post in which he served without pay. Mr. Hall has devoted his time since stepping down as party leader to his law practice.

Survivors include his wife, the former Gladys Dowsey, whom he married in 1934, of the home in Oyster Bay, a stepson, H. W. Carroll, of Port Washington, N.Y., seven grandchildren and one great-grandchild.* CAPTION: Picture, LEONARD HALL