Rep. Julian C. Dixon, 66, a highly respected California Democrat who had served since 1979 and was regarded as a thoughtful and authoritative voice on District affairs, died yesterday at a hospital in Los Angeles after a heart attack.

Dixon, who won reelection in his west Los Angeles district in November with 84 percent of the vote, was the ranking Democrat on the House Permanent Select Committee on Intelligence and a senior member of the Appropriations Committee, where he once chaired the subcommittee on the District.

Del. Eleanor Holmes Norton (D-D.C.) praised Dixon, who was born in the District, for his work on behalf of the city.

"Julian managed to serve two districts at once with his extraordinary wisdom, excellence and diligence: his own in California . . . and this city," Norton said in a statement. "Julian became a Californian when his parents took him there as a child, but he never ceased to be a Washingtonian." She characterized Dixon's role on the subcommittee as "a post of headaches, but no rewards."

Congressmen seldom seek the D.C. subcommittee; members are inundated with difficult and time-consuming work that their voters back home just don't care about. But Dixon won a seat on the powerful Appropriations Committee early in his career and almost immediately became a force on the D.C. subcommittee.

Early on, he tried to work with then-Mayor Marion Barry in obtaining federal aid for the District. But after 1995, with Barry back in office after a prison sentence, Dixon was neither as able nor as inclined to help. His party was in the minority, and he had become highly critical of the District government.

He joined others in calling for the federal government to simply take over some D.C. government responsibilities or for the privatization of some work, rather than simply giving the District more money. He was considered by many a tough but fair voice for the District, opposing both the Barry administration on some issues and more drastic measures publically favored by the Republican majority.

Fellow California representative Fortney "Pete" Stark called Dixon a true friend of the District. "He came to the defense of home rule, to the aid of the schools, health care, their police and fire departments," Stark said. "He felt a real responsibility, and he discharged that responsibility with great humanity."

Rep. Thomas M. Davis III (R-Va.) said he would remember Dixon for "his passionate concern for the people of the District of Columbia."

Dixon served as chairman of the Congressional Black Caucus in the 1980s and spent six years as chairman of the Committee on Standards of Official Conduct, known as the Ethics Committee. He was rules committee chairman of the 1984 Democratic National Convention.

He was also a member of the Defense subcommittee, from which he looked out for the interests of the Southern California defense industry. Also on Appropriations, he sought funds for Los Angeles area transportation measures, especially its commuter rail system. His success for California measures led to his being prominently mentioned as a possible candidate for Los Angeles mayor.

Perhaps the most difficult assignment for Dixon was his tour as Ethics Committee chairman in the late 1980s. He held that post when the House was being torn apart by the ethics investigation of its speaker, Jim Wright (D-Tex.).

With House Republicans, led by Newt Gingrich (Ga.), out for blood and Democrats putting up an equally partisan and combative defense, Dixon kept a judicious demeanor. He kept the Democrats and the Republicans of his committee together and let the evidence emerge, evidence that led to Wright's resignation in June 1989.

In more recent years, on the Intelligence Committee, he gained high marks from critics. Upon learning of his death, George J. Tenet, the director of central intelligence, issued a statement saying that Dixon's "tenure on the intelligence oversight committee was marked by a deep understanding and appreciation of our work."

"I sought and valued his advice," he said.

President Clinton released a statement calling Dixon a champion for the people of his district, state and nation, adding that he "earned the admiration and respect of all who knew him."

In recent years, Dixon also led efforts for federal aid to help Los Angeles overcome the effects of 1992 civil disturbances and to help victims of the 1994 Northridge earthquake. He also worked for passage of legislation establishing a memorial in Washington to the Rev. Martin Luther King Jr.

Dixon grew up in California. He was a 1962 graduate of California State University and a 1967 graduate of Southwestern University law school in Los Angeles. He was an Army veteran and had practiced law before entering politics. He served in the California Assembly from 1972 until entering Congress. He represented the state's 32nd District.

Survivors include his wife, Bettye Lee, and a son, Cary Gordon Dixon.