LOS ANGELES, SEPT. 25 -- Mary Astor, 81, the dark-eyed temptress of "The Maltese Falcon" and star of dozens of other films in a 42-year career, died of respiratory failure yesterday at a hospital in Los Angeles.

Miss Astor made her screen debut at age 14 in the silent movie era. She made more than 100 films, including "Dodsworth," with Walter Huston; "Prisoner of Zenda," with Ronald Coleman, and, in 1942, "The Great Lie," with Bette Davis, which garnered her a supporting actress Oscar.

But she was best known as the scheming adventuress who killed Sam Spade's partner amid intrigue over the treasure of "The Maltese Falcon." The 1941 John Huston film, costarring Humphrey Bogart, Sydney Greenstreet and Peter Lorre, became a classic.

Miss Astor was born Lucille Langhanke in Quincy, Ill., an only child. Her father was quick to realize the money-making potential of his beautiful daughter. He moved the family Hollywood where she got a contract and a new name in 1920.

Critical recognition came with her third film, a two-reeler called "The Beggar Maid."

John Barrymore then spotted a picture of the pretty teen-ager in a magazine and cast her opposite him in "Beau Brummel."

As the industry made the transition to sound in 1929, Miss Astor found herself out of work for 10 months. She made a bad sound test, but later she got some voice training and returned to work.

While her career picked up, her private life was rocky. Her first husband, director Kenneth Hawks, was killed in an airplane crash in 1931.

In 1935, her second husband, gynecologist Dr. Franklyn Thorpe, divorced her and was granted custody of their daughter, Marilyn. Miss Astor sued the following year to gain custody, and scandal broke.

Thorpe released excerpts from a diary that recorded in steamy, explicit detail Miss Astor's dalliances with other men. She maintained those pages were forged.

But some of their content, describing a love affair with playwright George S. Kaufman, was leaked to newspapers.

The material was sealed, and the judge awarded Miss Astor custody of the child for nine months of every year. The diary was destroyed by court order in 1952.

The custody fight boosted her career, and her best films followed, including "Dodsworth," "Brigham Young," "The Great Lie," "Meet Me in St. Louis" and 1949's "Little Women."

At the same time, she was drinking more and more.

Her 1937 marriage to Manuel del Campo, the father of her son Antonio, ended in 1942. She wed stockbroker Thomas G. Wheelock in 1945; they were divorced in 1955.

In 1949, Miss Astor was placed in a sanitarium for alcoholics. In 1951, police reported that she had attempted suicide with an overdose of sleeping pills, her third overdose in two years. She contended it was an accident. In 1953, she had to turn to the Motion Picture Relief Fund for help paying her bills.

She credited her recovery to the Rev. Peter Ciklic, a priest-psychologist. He encouraged her to write down her experiences as part of her therapy; they formed the basis of her 1959 autobiography.

Later she toured with stage productions, appeared on television and returned to films as the mother in "Return to Peyton Place."

She also tried her hand at fiction, writing six novels.

She spent her later years at the Motion Picture and Television Country House, the industry's retirement home in Los Angeles.