Actor John Wayne, 72, who symbolized off the screen the rugged American virtues he portrayed on it, died last night in Los Angeles.

Mr. Wayne, who was under treatment for cancer, died at 5:23 p.m. (8:23 p.m. EDT) at the UCLA Medical Center.

His death was announced three hours later by an official at the hospital who said Mr. Wayne's condition had been deteriorating over the last few days.

On Jan. 11, Mr. Wayne entered the medical center for what was to have been a gall bladder operation. During that surgery, which lasted nine hours, doctors also removed his stomach after discovering a malignant tumor there.

Eventually, the cancer spread throughout his body. He had been in a coma for 24 hours before his death, hospital officials said.

Mr. Wayne's seven children were at his bedside when he died.

One of the most popular film stars of all time, Mr. Wayne received in 1969 an Academy Award that recognized his entire career of more than 200 films as much as it did his portrayal of Rooster Cogburn in "True Grit," for which he was formally honored.

More recently Congress approved legislation to strike a gold medal reading "John Wayne, American."

For millions of moviegoers in this country and around the world who had watched his films since the 1920s, Mr. Wayne seemed the embodiment of those qualities of spirit and character that Americans aspired to and admired.

They were the frontier virtues, as Amercia knew them or believed them to be, energy, rugged honesty, self reliance, and a willingness - above all, perhaps - to fight for what he believed in.

Some captious critics complained over the years that Mr. Wayne did not act, that he only played himself. It scarcely mattered. The public like the roles he played on the screen and they like Mr. Wayne off the screen, seeing the film character and the public figure as one and the same - gruff, good-humored, plainspoken and admirable.

He was a native of Iowa, and moved as a child with his family to California. There he won a football scholarship to the University of Southern California and obtained a summer job at a tilm studio through his coach's Hollywood contacts.

Assignment as a member of the prop department to a film being made by director John Ford introduced Mr. Wayne to the Hollywood titans who were to have enormous influence on his future career.

In 1928, Mr. Wayne, whose birth certificate carried the name Michael Robert Morrison, made his film debut. It was a walk-on at the end of John Ford's "Hangman's House."

By 1930, Raoul Walsh, the noted director of action films, picked him to star in "The Big Trail." By then he was known as "Duke" Morrison. "Duke" was a nickname that remained throughout his career.

But Morrison had to go, at least in the view of Walsh, who wanted something he thought more suitable for a leading man.

"Duke," reportedly came from the name of the actor's pet Airedale. The name "John Wayne" stemmed from director Walsh's fondness for Revolutionary War hero Anthony Wayne.

The new name was no guarantor of success. "The Big Trail" was impressive but made little money. Many B westerns followed.

In 1939, John Ford cast him as the Ringo Kid in "Stagecoach," a classic western and a film landmark. It made Mr. Wayne a star.

Shortly afterward, World War II broke out. On the screen Mr. Wayne abandoned his Stetson for a steel helmet, but his character remained the same - bold, assertive, unyielding, heroic.

The first of his war melodramas was "The Fighting Seabees." Others were "Back to Bataan," "Sands of Iwo Jima," "Operation Pacific" and "Flying Leathernecks."

After the war came "Fort Apache," "She Wore a Yellow Ribbon," "Rio Grande," and "Red River," all westerns, and "The Quiet man," a raucous romance set in Ireland.

Subsequent memorable westerns included "The Searchers" and "Rio Bravo."

Some of the movies pleased both the critics and the audiences who kept Mr Wayne for 25 years among the top 10 film stars in terms of box-office drawing power.

"The Green Berets," for example, was scorned by many critics, but made money. "The Alamo" won approval from neither critics nor customers.

Yet non of the setbakcs seemed to inflict any permanent damage on Mr. Wayne's career or to tarnish his off-screen image.

What some perceived as a reactionary strain in his views was more widely recognized as an endearing brand of individualism, expressed by a man who believed in saying what he thought.

"I enjoy life to the extremities of my capabilities," he said in an interview a few years ago. "I enjoy humor, I have the inclination to trust people and I was raised by a man who said that lying was the only sin he couldn't forgive me for . . . "

On screen and off, he seemed sure of himself, amiable, always at ease.

"Things haven't always gone the way I wanted it," he said. "But I believe in the old 'relax and enjoy it.' It's the best you can do . . . "

Mr. Wayne's first bout with cancer came 15 years ago, when surgeons found a tumor in his left lung. Both the lung and two ribs were removed.

By the end of the year, he was able to call a press conference and assert that he had "licked the 'Big C.'" He went on to appear in many more films until he was stricken with cancer again last January.

Mr. Wayne's last public appearance was April 9, a poignant moment at the end of the Academy Awards show when the gaunt Duke walked onstage to present the Oscar for the best picture to "The Deer Hunter."

Mr. Wayne's appearance was greeted with a lengthy standing ovation by an audience full of his peers.

Thanking his audience in his familiar gravelly voice, he said the ovation was "just about the only medicine a fellow'd ever really need. Believe me when I tell you that I'm mighty pleased that I can amble down here tonight."Oscar and I have something in common. Oscar first came to the Hollywood scene in 1928. So did I. We're both a little weather-beaten, but we're still here and plan to be around for a whole lot longer."

Mr. Wayne was married three times. His first wife, Josephine Saenz, whom he married in 1933 was a Panamanian diplomat's daughter. They had four children and were divorced in 1946. That year he married Esperanza Baur, a Mexican actress. They were divorced seven years later. Mr. Wayne married Pilar Palette, in 1954 and had three children.

Funeral arrangements were incomplete last night. CAPTION: Picture 1, John Wayne in "Rooster Cogburn" (1975); Picture 2, In a typical role as a soldier; Picture 3, John Wayne as "Chisum" in 1970. UPI