The attitudes of the Reagan administration are "a reincarnation of the prejudices of prior centuries that relegated women to second-class citizenship," Senator Edward M. Kennedy `54 (D-Mass.) said yesterday to a gathering of women with careers in science.

Kennedy, who has sponsored and supported equal rights bills, called the Reagan administration's tax cuts in areas affecting women in scientific fields "regressive" at a reception in his honor at the Cronkhite Graduate Center.

In a short interview after the speech, Kennedy said that just at the moment when Americans are beginning to realize the importance of equal rights programs for women and important legislation being created, the administration is undermining such gains.

In his speech to about 200 people, Kennedy accused the administration of "wasting the talents of the nation's women. "He did however anticipate an eventual lessening of intolerance and a society which will have learned to use "our greatest untapped natural resource-the ingenuity, the intellect, and the insight of all Americans who are women."

Nancy F. Russo, the president of the Federation of Organizations for Professional Women, one of the reception's sponsors, called Kennedy a "stalwart friend, "because of his continuing support of women's issues. "He's always there when you need him." Russo said, adding. "We're fools if we don't support him."

In 1980, Kennedy introduced the Women in Science and Technology Equal Opportunity Act to encourage women to pursue careers in Science and Technology. Because of budget cuts, only one of the Act's programs--granting visiting professorships for women in research-will be funded this year.

After his speech, the Federation presented Kennedy with a poster portraying distinguished women and the Association for Women in Science, another sponsoring group, gave him a pin in recognition of his support, participating in the conference, either an ad from as far away as Berkeley, California and wires.