The results are important because they can be used by local officials nationwide who are working to get restaurant smoking bans passed or existing laws strengthened, according to the study's researchers and anti-smoking advocates.

The findings were published in the January issue of The Journal of Public Health Management and Practice. Composed of several research papers, they were funded by The Substance Abuse Policy Research Program.

The program is supported by Princeton, N.J.-based Robert Wood Johnson Foundation, which is devoted to improving health care and reducing substance abuse, including tobacco.

The findings were based on taxable sales receipts from New York City and Massachusetts restaurants. Although there have been earlier studies of smoking bans, this research is the first to examine New York City, the nation's largest dining market with more than 22,000 restaurants.

New York City's Smoke-Free Air Act was signed into law in January 1995 and bans smoking in restaurants with more than 35 indoor dining seats. Smoking is allowed in bar areas of those restaurants if they are separated from the dining space.

Many New York restaurant owners joined the tobacco industry in trying to fight the law, saying it was bad for business and would result in a loss of jobs.

However, the analysis showed that sales in New York City restaurants have increased by 2 percent since the anti-smoking law became effective. In the rest of New York State, where smoking laws are less stringent, sales decreased by 4 percent.

Between 1993 and 1997, the city gained 19,347 new restaurant jobs, an 18 percent increase. The number of restaurants in the city rose 6 percent during this period.

Dr. Andrew Hyland, a Roswell Park Cancer Institute researcher who worked on the study, said a survey of diners showed the majority had not cut back on restaurant visits.

"Some smokers did report dining out less frequently, but non-smokers, who out-number smokers four to one, reported dining out more frequently," he said.

Michael O'Neal, of O'Neal's Restaurant near Lincoln Center, said he felt many of his colleagues were misled by Big Tobacco into believing the ban would hurt business.

"I'm tired of my business being used by the tobacco industry," O'Neal said, adding that if 75 percent of consumers do not smoke compared with 25 percent who do, the anti-smoking ban would be good for business. "It's simple math," he said.

Waldy Malouf, who was chef director at the Rainbow Room until it recently changed ownership, said there had been no adverse effect. He said concerns there would be a drop in orders for desserts and after dinner drinks proved unfounded.

Malouf, who will be opening two restaurants in Manhattan, said the ban was good because it eliminated the need for separate seating sections.

The research of Massachusetts restaurants found that, on average, restaurant revenue in smoke-free towns rose 4 percent. Restaurant revenues in communities that did not severely restrict smoking rose 2 percent over the same period.