Miriam Ottenberg, 68, a Pulitzer Prize-winning investigative reporter for The Washington Star, died of cancer Nov. 9 at Georgetown University Hospital.

Her Pulitzer, won in 1960, was for a series of articles exposing the practices of unscrupulous used-car dealers in the Washington area and for follow-up stories that led to the enactment of remedial laws.

When she first learned she had cancer two years ago, her response was to plan a book about people who had conquered the disease. It was the same response that she had when, 20 years earlier, she was stricken with multiple sclerosis.

She never wrote the book on cancer. But "The Pursuit of Hope," the first of its kind on multiple sclerosis, was published in 1978. In it she described her own battle and that of others against the crippling effects of the disease that forced her to retire from The Star in 1975.

Through both her MS and her fatal bout with cancer, Miss Ottenberg maintained what she called an "upbeat attitude," continuing her yearly trips on freighters to exotic areas of the world that fascinated her "from Zanzibar and Tanzania to the Straits of Magellan to see the penguins in their natural state."

In 1962, she had written another book, "The Federal Investigators," that grew out of her experiences covering crime, corruption and subversion on the national level.

Miss Ottenberg was born in Washington and lived in the city all her life. Her parents were Louis and Nettie Podell Ottenberg. He was a lawyer and a founder of the Anti-Defamation League of B'nai B'rith. She was a social worker who was active in behalf of a number of causes, including child day care. A grandfather, Isaac Ottenberg, founded the Ottenberg Bakery.

She was a graduate of the old Central High School and attended Goucher College and Columbia University. She graduated from the University of Wisconsin with a degree in journalism and later was honored by the school for distinguished service to journalism.

Miss Ottenberg started her career on The Star in 1937 as a police reporter, an unusual assignment for a woman in those days, and developed it into an investigative beat.

In 1963, she broke the biggest crime story in years, the revelations of Joseph Valachi, an underworld figure who disclosed to the FBI the inner workings of the "Cosa Nostra," the crime syndicate that dominated a network of mobs in more than a dozen cities.

She delved into white collar crime and consumer fraud, often working under cover as a potential victim. On the local level, she explored fraudulent baby brokers, phony marriage counselors, fake charities, shoddy investment firms and the home improvement racket. Her stories often were followed up with campaigns for corrective laws.

She received numerous journalistic honors, including eight awards from the Washington Newspaper Guild. The walls of her apartment were lined with framed citations for services and contributions to the community from her writings.

Miss Ottenberg once summed up her feelings about her role as a journalist: "A reporter should expose the bad and campaign for the good. That's the way I was brought up."

Miss Ottenberg was a member of the Washington Press Club and was its president in 1964. In swearing her in as president, Robert F. Kennedy, who was then attorney general, said: "Justice is usually pictured as a tall woman, blindfolded; but The Star's adaptation is a small, slender woman, who is certainly not blindfolded."

Survivors include a sister, Regina Greenhill of North Miami Beach, Fla., and a brother, Louis Ottenberg Jr. of Bethesda.