The counseling centers for Vietnam veterans constitute a success story.

They do a land-office business. Two hundred thousand veterans have patronized them since the first opened in 1979. The number of applicants has increased steadily. In the first six months of 1983, 35,000 veterans sought out the centers, 10,000 more than in a comparable period the year before.

Part of the reason is unemployment: as of June, 619,000 Vietnam veterans were jobless.

But it goes deeper than that, according to Dr. Arthur Blank, who runs the counseling service for the Veterans Administration.

"They are accepted," he said of the centers, "by the vets, their families and the mental health professionals."

Congress, which has reason to feel guilty about its role in the Vietnam war, has favored the centers since their inception.

The House passed, without debate, a measure introduced by Rep. Bob Edgar (D-Pa.) for a $30 million appropriation and a three-year extension for them. Not even the most hidebound fiscal conservative holds up the program, which cost $9.9 million in its first year, as an example of the oft-repeated fact that federal programs, once started, are as hard to stop as wars.

The VA, which once gave the rap centers a cold shoulder, is proud of them.

The mental health community, which couldn't deal with the "delayed stress syndrome" that afflicts so many veterans, and therefore denied its existence, has many members working in the 135 centers that are flourishing around the country.

The Reagan administration, which in 1981 tried to eliminate the centers--Office of Management and Budget Director David A. Stockman thought they were another federal frippery--has not raised a hand against them lately.

The veterans' organizations, which were baffled and irritated by veterans who didn't brag about their service, have become rooters for the centers.

Blank, a former associate professor of psychiatry at Yale, has headed the counseling service since 1982.

He is a Vietnam veteran who served as an Army psychiatrist in Ben Hoa in 1965 and 1966 and has observed with a professional eye the evolution of attitudes toward the men who fought the nation's most unpopular war. It took a long time for the public to adjust to these veterans.

His mental health colleagues were part of the problem. Many had never encountered veterans. And the Vietnam vets, who had a high incidence of divorce, drug abuse, alcoholism and unemployment, were beyond them.

Many of the doctors called upon to treat Vietnam veterans were of World War II vintage and resented veterans with low opinions of themselves and their country. Those in the starched white coats who were the vets' contemporaries had gone to considerable pains to avoid going to the war, and looked down on those who went.

And their training offered them no clues on handling delayed stress. The American Psychiatric Association Diagnostic and Statistical Manual had no entries on stress until its 1980 edition.

"We had plenty of studies from World War I and World War II about stress that showed up 20 or 30 years later," Blank said. "Those veterans had nightmares and flashbacks, too. But only 3 or 4 percent were affected. In Vietnam, the rate is 20 to 25 percent. The difference is that Vietnam vets came home to hostility."

It was the Vietnam veterans who found the way out of the pits, and provided the models for the counseling centers. About 1975, despairing of getting help from the white coats, they began founding self-help centers. They set up storefronts where vets could hang out and talk about things that nobody who hadn't been in the Vietnam war wanted to hear about.

They tried to find jobs for each other, tried to explain to wives and mothers why "the brothers" were sometimes hard to get along with and tried to figure out what the war had been about.

When Max Cleland, the triple-amputee Vietnam vet appointed by President Carter to be chief of the VA, organized the first official centers, he asked the heads of self-starting counseling centers to lead the way.

"What we do is try to find something positive in their experience, bad as it was," Blank said. "A lot of them are proud of their units and the way they functioned. What's positive is the way they help each other. They are stronger, more compassionate than most people. Anti-war vets, pro-war, they all come and have it out."

The continuation of the centers is an acknowledgement that Vietnam veterans are different. Their record is beginning to suggest that they also may be special.

They seem to be more brotherly than other veterans, and they do for themselves and each other in an unprecedented way. They put up their own memorial, they held their own parade and they have instructed the country in how to deal with the emotional problems that come from serving in a war that people later decided was a bad idea.