Taboos once limited sex talk to whispered conversations. Today, sex is part of a frank, nationwide dialogue often conducted in newspapers and on television. Yet numerous comments received in the Washington Post reader poll suggest that many people don't know where to turn for help with sexual problems. Some resources include:

* American Association of Sex Educators, Counselors and Therapists (AASECT), a nonprofit organization that certifies health professionals and offers a national register of certified members for $10. Write to AASECT 11 Dupont Circle, Suite 220, Washington, D.C. 20036.

* Society for Sex Therapy and Research (STAR). Referrals are available by sending a stamped, self-addressed envelope to Dr. Alan J. Wabrek, c/o STAR, Hartford Hospital, Hartford, Conn. 06115.

*essionals. P.O. Box 29795, Philadelphia, Pa. 19117 (215-782-1430).

* Sex Education Information Council of the United States, which provides read Education Information Council of the United States, which provides reading lists of sex-related topics for a nominal fee, 80 Fifth Ave., Suite 801, New York, N.Y. 10011 (212-673-3850).

Sex therapy is generally short-term, usually lasting 10 to 20 weeks. It costs between $50 and $100 an hour and can sometimes be covered by medical insurance, depending on the insurance policy and the diagnosis.

Since anyone can hang a shingle out and claim to be a sex therapist, experts advise asking prospective sex counselors about their education, training, background. "I don't believe that any competent person should object to those questions ," says Joseph Lo Piccolo of Texas A & M University. Moreover, all who offer therapy should also be licensed health professionals.

And "if there's any indication of sex between the therapist and the patient, the patient should immediately leave and file an ethical complaint," Lo Piccolo says.