Duke Zeibert, 86, the Washington restaurateur whose downtown establishment became an institution and a favorite gathering place for the well-connected and the well-known, died yesterday at his home in Bethesda. He had cancer and heart ailments.

For almost a half-century, Zeibert presided over hundreds of thousands of lunch and dinner meetings in which politicians, power brokers, sports figures, business executives, media stars and entertainment celebrities came together to break bread, sip wine, schmooze, see and be seen.

He opened the first Duke Zeibert's restaurant at 17th and L streets NW in 1950, and he operated at that location for 30 years. In 1980, when the building was torn down, he retired to play golf and the horses. But retirement bored him, and in 1983 he opened a new Duke Zeibert's on the second level of the Washington Square building at Connecticut Avenue and L Street NW. He remained there until retiring for good in 1994.

As places to eat, both the original and the new Duke Zeibert's were known for their trademark sour and half-sour pickles, bread baskets with lightly seeded onion rolls, boiled beef, matzoh ball soup, chicken in the pot, crab cakes, potato pancakes and brisket.

As places to meet, they were known for their clientele. President Harry S. Truman and FBI Director J. Edgar Hoover dined there, as did assorted Kennedys and President Clinton. Washington Redskins owner Jack Kent Cooke was a regular, as were Robert S. Strauss, the former Democratic Party chairman and ambassador to the Soviet Union and the Russian federation, and talk show host Larry King.

Strauss recalled Zeibert as "a restaurateur of the old school."

"He didn't try to be something he wasn't," Strauss said. "He had the ability to make you laugh at life and at yourself. And he always had the ability to laugh at himself. He understood people. He worked at it, and he worked at his job. And he loved it.

"Once in a while, he'd buy you a drink and then he'd say he must be getting sick. I think some of the life and sense of humor of the national capital was lost when he retired and now even more so that he died."

King called Zeibert a "throwback to the old days when the owner of a restaurant was at the restaurant. But even more than that, there was never a better friend."

David George Zeibert was born in Troy, N.Y., and he began his career in the restaurant business as a dishwasher in the resorts of New York's Catskill Mountains. Later he bused tables and then worked his way up to headwaiter.

In the 1940s, he worked at Fan & Bill's restaurants in Washington, Miami and Upstate New York. He got his nickname for the white silk pants he wore to work at a Miami restaurant.

"The other waiters made fun of me. They kept asking me, Who do you think you are, a duke?' " the Associated Press quoted him as saying. "I was suddenly the Duke.' "

Opening his own business in 1950, Zeibert cultivated a customer base energetically and successfully, and he presided over his dining rooms with panache and aplomb, employing handshakes and pats on the back, a repertoire of jokes and an innate sense of who was who.

He was a master at working a room, and he knew how to mix people. "Duke would always make sure you knew who was in the place," Bill Regardie, the publisher of Regardie's magazine, said in a 1993 interview.

"The place was electric," recalled sports publicist Charles Brotman. "It was so wonderful to have Duke meet and greet you. He made everybody feel important. It was something very special. He almost always sat at everybody's table. He'd tell you the latest gossip, and you'd tell him the latest gossip. Everybody knew what was going on around town because they heard it first at Duke Zeibert's."

In time, Duke Zeibert's restaurant would become known as a place where deals were made and broken, reputations were made and lost, careers advanced and declined.

Former ambassador Strauss was host for a 1993 meeting there between Clinton and then-Senate Majority Leader Robert J. Dole (R-Kan.). George Bush dined there during his presidency.

Power lawyer Edward Bennett Williams, oddsmaker Jimmy "the Greek" Snyder and sportswriter Morrie Siegel were frequent customers.

A natural showman, Zeibert was a tireless promoter of his restaurant. In 1987, when Soviet leader Mikhail Gorbachev left his Zil limousine to work the crowds at Connecticut Avenue and L Street during a state visit to Washington, Zeibert spotted him from a restaurant window shaking hands in the street below.

"Come on up for lunch. We've got borscht," he shouted to the Soviet leader.

Six years later, in November 1993, Gorbachev did get to eat at Duke Zeibert's. He had dinner there with King, interrupting a meal of pickled herring to kiss the bride as a wedding party emerged from one of the back rooms.

Zeibert was delighted.

"He loves my pickles. He loves my pickles. He's eating them just like popcorn," the restaurateur shouted to anyone who would listen.

When not running his restaurant, Zeibert often was found on the golf course or in the card room of the Woodmont Country Club. His avocations included betting on card games, and in 1984, he was among 14 men arrested by Rockville police on gaming charges resulting from a raid on the Progress Club, located at the rear of Congressional Plaza on Rockville Pike.

The charges were dismissed after Zeibert and the others performed community service. "I've been playing cards since I was 6 years old," Zeibert said at the time. "They're not going to stop me from playing bridge for money or master points."

In 1946, Zeibert married Joan Singer. They later were divorced.

A daughter, Sharon Zeibert, died in 1980.

Survivors include two children, Randy Zeibert and Terri Sanker, both of Potomac; and five grandchildren. CAPTION: DUKE ZEIBERT