Since Dwight Eisenhower lived in the White House, Seminary Hill residents have been fighting a proposed addition to Alexandria Hospital that would house doctors' offices. Early yesterday, their three-decade-long effort seemed a triumph.

The Planning Commission voted 4 to 2 to reject a $12 million, four-story addition to the Seminary Road hospital that included 60 physicians' offices.

"You bet we're happy. Somebody listened to the people," said Jack Sullivan, a leader of the opposition.

"It's deja vu for me," said former mayor Charles E. Beatley, who entered politics in the late 1950s because of his opposition to hospital expansion.

Through the years, although residents have managed to thwart office development plans, the hospital has always refused to take "no" for an answer. This time, however, many are convinced that if the Planning Commission and the City Council reject the plans, the hospital will finally drop the office plans.

Because the council, which is scheduled to vote on the issue June 18, generally follows the commission's recommendations, yesterday's vote was considered a major victory for residents.

"I'm kind of surprised," said A. George Cook, president of the Alexandria Health Services Corp. "They {the commissioners} seem more interested in short-term gain than the long-term benefit of receiving quality medical care."

Residents, who attended a marathon meeting that ended after 1 a.m., argued that doctors' offices would draw thousands of unwelcome cars each day. Worse, they said, it would introduce commercial business to the neighborhood, where many homes sell for more than $250,000.

Alexandria Hospital is a 115-year-old nonprofit facility originally in Old Town. Since it moved to Seminary Road in 1962, it has tripled in size.

Most neighbors opposed only the offices and not the proposed 7,000-square- foot surgery center or the portion of the 108,000-square-foot doctors' office building that would be used for outpatient and cancer care.

Planning Commission members agreed. "It's the doctors' offices that are hard to swallow," said Mitchell Griffin.

The commission was not swayed by a consultant's report, ordered by the City Council, warning that an increasingly competitive health care market could cost Alexandria Hospital as much as $13.8 million in revenue in the next five years.

A burgeoning outpatient care business that is emptying hospital beds across the country and the proliferation of large health maintenance organizations such as Kaiser Permanente pose severe financial problems for the hospital, the Lewin and Associates report said.

Hospital officials argued that doctors' offices would boost the hospital because physicians refer most patients to the facility closest to their office. They also said Alexandria Hospital is the only Northern Virginia hospital without doctors' office buildings attached to it or adjacent to it.

But commission member Allan Kamerow said he was not convinced that doctors' offices would solve whatever financial problems the hospital had.

Alexandria Hospital is using 360 of its 414 beds. Annually, it admits 15,000 patients, serves 42,000 emergency cases, and treats 40,000 outpatients.