Benjamin S. Rosenthal, 59, a New York Democrat who earned a reputation for steadfast and sharp-tongued advocacy for the consumer at home and for Israel during a 20-year career in the House of Representatives, died of cancer yesterday at Georgetown University Hospital.

Mr. Rosenthal was elected to the House in a special election on Feb. 20, 1962. He was a member of the Government Operations and Foreign Affairs committees and these gave him forums from which to pursue his principal interests. He did so not only with diligence, but with a dramatic flair that drew national attention to the issues he raised and to himself as their champion.

"One congressman with a fair amount of chutzpah can awaken the public conscience," he once said.

His own chutzpah led him to hold hearings in which it was disclosed that the entire $10 deposit of a child in a bank had been eaten up by service charges and in which the grocery bill of a black resident of an inner city was shown to be higher than that of a housewife buying similar items in a supermarket in a prosperous suburb. He sought legislation protecting condominium buyers and in other ways took up the cudgels for the little man.

In 1981, he bearded Budget Director David Stockman in connection with efforts of the Reagan administration to cut back the powers of the Federal Trade Commission. Plans to accomplish this through the budget were "a rather nefarious shortcut" around Congress, Mr. Rosenthal said.

In foreign affairs, he was an outspoken supporter of Israel, always seeking more aid for that country on more generous terms. By the same token, he opposed administration efforts over the years to improve relations with Arab governments.

In 1979, he was against plans by President Carter to sell tanks and planes to Arab nations. In 1981, he tried to persuade his colleagues to block Reagan's sale of AWACS early warning planes to Saudi Arabia.

In the era of Vietnam, he was a militant critic of the war. In a speech to the House in 1969 he asserted that the United States had become "virtually the puppet" of the Saigon government. His stand on the war drew the wrath of President Johnson.

Mr. Rosenthal lost his longest battle in Congress. This was a 14-year campaign to establish a federal agency that would represent consumers and their interests in courts.

On one occasion the measure passed both the House and the Senate, but the leadership refused to send it to the White House on the grounds that President Ford would veto it--and those favoring the bill lacked the votes to overcome a veto. The issue died in 1977 when House Speaker Thomas P. (Tip) O'Neill (D-Mass.) declared that he would not permit a new measure to come up for action.

When Mr. Rosenthal found himself thwarted, he was capable of launching drives for the removal of committee chairmen who stood in his way. Thus he tried to unseat Rep. Clement J. Zablocki (D-Wis.) as chairman of the House Foreign Relations Committee and he tried to do the same with Chet Holifield (D-Calif.), a former chairman of the Government Operations Committee. He fell out with Holifield when the Californian killed a consumer investigating panel of which Mr. Rosenthal was chairman. In 1975, when Rep. Jack Brooks (D-Tex.) became chairman of Government Operations, the panel was reconstituted.

These and similar activities earned for Mr. Rosenthal the condemnation of some of his colleagues. With a wit and a gift for not taking himself too seriously, he readily admitted that he could indeed be difficult.

"I do think there are some people who think I'm abrasive," he said. "In some ways, I think I'm abrasive. You can't change your personality."

At Mr. Rosenthal's death, Chairman Brooks said: "He contributed immeasurably to the work of our committee, especially as chairman of the commerce, consumer and monetary affairs subcommittee. He had a deep and abiding concern for protecting the poor and the powerless." Consumer advocate Ralph Nader said: "He displayed unmatched leadership in his consistent support of consumer justice over the past 20 years."

Benjamin S. Rosenthal was born in New York City on June 8, 1923. He attended Long Island University and the City College of New York. He served in the Army in World War II and later earned law degrees at Brooklyn Law School and New York University. He practiced law in New York and became active in the Democratic Party in the Queens. He went to Congress in 1962 following the resignation of representative Lester Holtzman, who was appointed to a state court judgeship.

One of his first assignments on Capitol Hill was to the Agriculiture Committee. This produced some jokes about flower pots and garden plots in the Queens. But Mr. Rosenthal turned the assignment to his own advantage--and so launched his career--when he was named to a food marketing commission. Through this he became interested in the impact that government policies have on consumers.

Mr. Rosenthal's survivors include his wife, the former Lila Moskowitz; two children, Edward Rosenthal and Debra Rosenthal Mandel; his mother, Ceil Rosenthal, and a sister, Lola Ostreicher.