The U.S. Equal Employment Opportunity Commission has ruled that six white D.C. Fire Department officials were victims of racial discrimination when they were denied a promotion eight years ago in favor of a black officer who later became fire chief.

In a ruling fire officials said is the first of its kind here in recent memory, the commission found that Jefferson W. Lewis should not have been advanced from battalion chief to assistant fire chief in 1974 ahead of the six white officers, five of whom had more seniority and higher rank.

An investigation of Lewis' promotion to head of fire operations, skipping the rank of deputy chief, revealed that reasons city officials gave for declining to advance one of the white officers were groundless and that officials "failed to perform any careful analysis of the qualifications of the candidates for the promotion," the commission said.

Lewis, who four years later became the second black fire chief in the city's history when he was chosen by then-mayor Walter E. Washington, retired after serving 20 months in the job.

The ruling could have sweeping implications for promotion practices in the fire department, which for years has been torn by racial controversy.

Of approximately 1,400 fire fighters on the force, about 400 are black. Though blacks rarely have filled more than 15 percent of the department's highest level jobs, since the early 1970s the city's mayors consistently have appointed a black as fire chief.

Some white fire officials have complained that this trend in mayoral appointments, while perhaps politically advantageous, has undermined the merit system, shut off hopes of whites aspiring to the department's top post and shattered morale. Some black firemen, meanwhile, maintain that discrimination against blacks is widespread and that hiring and promotion in the department should reflect the racial makeup of the city, which is about 70 percent black. The fire department is about 32 percent black.

Officials of the predominantly white Fire Fighters Association, who consistently have argued against setting for the department what they see as racial quotas, said yesterday they were unable to assess what immediate effect the ruling might have. They acknowledged, however, that it would play an important role in future debates over promotion practices.

"It's going to send a signal, and we're going to use it to send a signal," one official said privately.

Under the commission's ruling, the six officers, all of whom retired within a year of Lewis' promotion, have 10 days to notify the commission whether they will meet with city officials to try to reach a settlement.

"They city officials absolutely have to get the merit system back in and stop racism as a basis for running the fire department," said Floyd E. Yocum, former battalion chief at the department's training academy. "It just makes me sick what's happened to my fire department."

"We've been vindicated," said former fire marshal John Breen. "Whatever the remuneration is, it would have to be considerable to make up for what was done to us."

Ray Alfred, past president of the predominantly black Progressive Firefighters Association, said of the ruling: "It's going to force us to take a closer look at the procedures."

Lewis was the department's third black to become a captain when he was promoted to that rank in 1965. His promotion to assistant chief in 1974 placed him in charge of all fire fighting operations, though five of the officers who filed the grievance had three to nine years more experience.

His appointment as chief in 1978 was opposed by both the Fire Fighters Association and the Progressive Firefighters Association.