In 1961, if you wanted to see a sex therapist, you were out of luck -- the field did not even exist.

Today, however, sex therapy is a growing specialty with several thousand sex therapists in practice nationwide. Some 60 sex therapists practice in the Washington metropolitan area alone.

Yet the field still suffers from an important problem: Anyone can hang out a shingle and claim to be a sex therapist because neither the federal nor state governments license the practitioners of this field.

The American Association of Sex Educators, Counselors and Therapists and other organizations are working to solve this problem, but until they do, experts offer the following tips to find qualified and reputable sex therapists: Call a local medical school or university hospital for a referral, "if you really want to be safe," advises Dr. Helen S. Kaplan, director of the human sexuality program of New York Hospital. All medical schools are required to teach a course on sexuality. The people who teach these courses are generally knowledgeable about qualified sex therapists practicing in the area. Ask your family physician, obstetrician-gynecologist, urologist or psychotherapist for a referral. Friends and relatives who have successfully completed sex therapy can also be helpful in finding a sex therapist, provided that you -- and they -- feel comfortable discussing the subject.

Once you have the names of several sex therapists, it is important to interview them. Good sex therapists will encourage this practice.

In your evaluation, keep in mind how comfortable you feel with the person or team of therapists. The working relationship you develop is known as therapeutic alliance and is crucial to determining how successful the therapy will be.

The best results from sex therapy occur when both partners participate, experts say, since it is the relationship, not the individuals who are treated. But if you are single, or if your partner won't participate, most sex therapists will still offer treatment.

Experts also recommend that you: Pay attention to details. Are there diplomas and a state license on the wall? How about journals and books that would indicate that the therapist is keeping up with the field?Ask questions, especially about credentials. Good therapists expect questions about their background and educational degrees. Find out where the therapist trained and for how long. Ask how long the therapist has been practicing. What proportion of the therapist's practice is devoted to sex therapy? Does the therapist attend continuing education courses? Is the therapist a member in good standing of a professional organization, such as the Society for Therapy and Research, the American Psychological Association, the American Psychiatric Association or the National Association of Social Workers? Another plus: finding someone who is certified by a professional organization such as the American Association of Sex Educators, Counselors or Therapists. Discuss fees, health insurance coverage and general length of treatment. Sex therapy usually costs between $50 to $100 per hour session. Treatment is usually brief, ranging from a few weeks to about six months. At the Masters and Johnson Institute, sex therapy is conducted in a two-week intensive treatment that runs about $2,500 per couple. Masters- and-Johnson-trained sex therapists -- including the District-based Dr. Armando DeMoya and Dorothy Demoya -- also offer this intensive therapy. Many health insurance policies that pay for psychotherapy will also pay for sex therapy.

To determine how well your personality fits with the sex therapist -- or with any other psychotherapist -- Michigan psychologist Dr. Steven Charles Fisch suggests asking yourself: Did you feel that you and your partner were taken seriously and were treated with respect? Do your instincts tell you that this is a person you can trust -- one whose basic skill, experience and sensitivity are comforting? Did you feel the therapist was sincere and genuine in the way he or she related to you and to your partner? Did the therapist respond to your questions in a thoughtful and considerate manner?

Finally, remember that reputable sex therapists consider sex absolutely forbidden between therapist and patient.

If a sex therapist makes such a proposition, "run -- don't walk -- out of the office," advises Dr. William Masters, head of the Masters and Johnson Institute in St. Louis, who encourages reporting such people to the appropriate professional association and the police. "Any physical interaction between therapist and patient is not only unethical, but as far as I am concerned it is also statutory rape."