Nora Ephron, who cast an acerbic eye on relationships, metropolitan living and aging in essays, books, plays and hit movies including "Sleepless in Seattle" and "When Harry Met Sally," died Tuesday in New York. She was 71.

Ms. Ephron died at New York Presbyterian Hospital, where she was being treated for acute myeloid leukemia and pneumonia. Ms. Ephron directed eight feature films, including "Sleepless in Seattle" and "You've Got Mail" (both featuring Tom Hanks and Meg Ryan) and had screenplay credits on more than a dozen productions. She earned three Oscar nominations — for writing "Sleepless in Seattle," "When Harry Met Sally" and "Silkwood." As a playwright, she wrote "Imaginary Friends" and, with her sister Delia, "Love, Loss, and What I Wore."

Ms. Ephron also wrote extensively about her own life, often in a sly, self-deprecating style. Her books included "I Feel Bad About My Neck: And Other Thoughts on Being a Woman," "I Remember Nothing: And Other Reflections," "Crazy Salad: Some Things About Women," "Wallflower at the Orgy" and "Heartburn," a roman à clef about her marriage to Watergate journalist Carl Bernstein.

Even though she wrote strong female characters and said male filmmakers had little interest in women besides "girlfriends or wives," Ms. Ephron's brand of feminism was winking rather than strident. At a Hollywood awards event several years ago, she looked about the room and said, "When they write the history of the feminist struggle in America, I always wonder how this lunch will exactly fit in. We are definitely the best-dressed oppressed group."

Ms. Ephron continued to work steadily. "Julie & Julia," a film biography of chef Julia Child told through the eyes of a young admirer, was released when Ms. Ephron was 68. Adapted from Child's autobiography and a cooking memoir by Julie Powell, the film took in nearly $95 million at the U.S. box office.

Ms. Ephron was born in New York City and grew up in Beverly Hills, the oldest child in a family of writers. Her parents, Henry and Phoebe Ephron, wrote screenplays, and based Sandra Dee's college-girl character in the 1963 comedy "Take Her, She's Mine" on Nora's letters home from Wellesley College in Massachusetts. Ms. Ephron's sisters Delia and Amy are also screenwriters; sister Hallie is a journalist.

After graduating in 1962, Ms. Ephron worked for a short time as an intern in the White House during the presidency of John F. Kennedy, noting she was "probably the only young woman who ever worked in the Kennedy White House that the president did not make a pass at."

She was a reporter at the New York Post, before writing columns in the 1970s for Esquire and New York magazines. She promptly established a sharp and witty voice as a writer.

Ms. Ephron's first marriage, to writer Dan Greenburg, ended in divorce. In 1976, she married Washington Post journalist Bernstein, and moved to Washington. Three years later, while pregnant with their second child, she discovered Bernstein was having an affair.

In 1987, she married the writer Nicholas Pileggi.

It was in 1989, with the release of "When Harry Met Sally," that Ms. Ephron firmly established herself as Hollywood's mother of the modern romantic comedy, carrying the escapist, fast-paced style of 1930s screwball comedies into the 20th century by tackling subjects such as divorce and email. She said that all romantic comedies were essentially mashups of Shakespeare's "The Taming of the Shrew" and Jane Austen's "Pride and Prejudice," but she injected the formula with a somewhat sentimental flavor.

Survivors include Pileggi and sons Jacob and Max Bernstein.