BOSTON, JULY 8 -- -- Kitty Dukakis, wife of Massachusetts Gov. Michael S. Dukakis, a candidate for the 1988 Democratic presidential nomination, today acknowledged a 26-year dependency on prescribed diet pills, a habit she said she overcame five years ago.

"Today is a special day for me," Kitty Dukakis, said at the dedication of a drug and alcohol treatment facility for adolescents. "Five years ago, I went to a treatment center in Minnesota for treatment for dependency on diet pills that I had been taking since I was a teen-ager," she said. "To explain my absence, I came up with the idea of telling people I had hepatitis.

"I have not taken any since. I am now drug-free and I have been for five years. Today I want to share my story with you because I hope it will help others who face the same problem I did."

Dukakis strongly supported his wife's disclosure. "This is something she wanted to do and something she had to do that she felt good about doing," he told a statehouse news conference. "I'm very proud of her.

"She has done something which a lot of people have struggled with. She is one of literally hundreds of thousands of people who have found themselves in the same kind of situation."

Dukakis defended the use of a cover story about hepatitis during the 1982 gubernatorial campaign, saying the problem was "not a deep, dark secret. Many people did know about it and helped her."

But Dukakis also said his wife "expressed a very strong desire that if she was to solve this problem, if she was to cope with this dependency, it would have to be in private.

"My life is an open book. My health history is an open book. My wife's and children's and relatives' health history are not relevant to my capacity to serve," he said.

Asked by reporters if he had any dependencies of his own, Dukakis firmly answered "No," but added that the question was appropriate in light of Gary Hart's withdrawal from the presidential race following allegations of extramarital relationships.

Kitty Dukakis said she started taking pills in 1956 at the age of 19. "I wasn't fat, but -- like many women, then and now -- I was worried about my weight. I went to a doctor who prescribed amphetamines."

She said she tried to quit twice, but failed, and had hid her dependency from her husband. " . . . I didn't tell my husband because I knew that if I did, I would have to confront my dependency. I would have to stop. And I knew I wouldn't be able to stop."

She said her husband was understanding when she revealed the problem to him during the course of his 1982 gubernatorial campaign, despite fears that the problem could harm his political career.