Over the past year I've met three self-identified lesbians with HIV. All three believed they could trace their infections back to a male partner. Since we already know male-to-female transmission is easier than female-to-male transmission, I started to wonder about female-to-female transmission. Are lesbians at risk of contracting HIV from one another?

The Centers for Disease Control have documented a handful of cases of woman-to-woman transmission. HIV is in vaginal juices and menstrual blood, so yes, the risk is real. Unfortunately, after two decades into this epidemic, no published studies exist examining the risks for women who have sex with women. Worse, of more than 100,000 female AIDS cases reported through 1998, the data about whether those women had sex with other women is missing in half the cases. Either the doctor didn't ask or the patient didn't tell. Via sloppy research or perhaps through sheer indifference, the CDC does not include female-to-female transmission in its AIDS reports. As a result, many lesbians mistakenly believe they are not at risk.

HIV is transmitted when blood, vaginal fluids, breast milk or semen from an infected person enters your bloodstream. So it follows that lesbians can be infected with HIV through having unsafe sex (with women or men), sharing injectible drug works (needles), and piercing and tattooing with unsterilized equipment. Still, given the total lack of data on transmission between women, many lesbians who only have sex with other lesbians may view the whole risk scenario as completely hypothetical.

Time for a reality check: Whether sexual behaviors are safe or unsafe depends on the chances of your partner's bodily fluids coming in contact with your blood. Women who have sex with women might want to consider these guidelines:

• Wet kissing is safe unless either of you have sores or cuts in your mouth or bleeding gums. After you brush your teeth or floss, wait a half an hour or so before kissing.

• Touching your lover's breast, massage, and body to body rubbing are safe -- as long as no suckling of breast milk is involved.

• Cuts or sores in the mouth can increase risk during oral-vaginal (lips, tongue and mouth on vagina) and oral-anal contact (lips, tongue and mouth on anus). Unprotected oral sex is especially risky when your partner has her period, a vaginal infection or a rectal discharge involving blood. To make it safer, cover her genital area (vulva) or anus with a latex dam (also known as a dental dam), or cut open a condom to make a barrier. You can also use clear Saran Wrap as a barrier. (The non-microwavable kind only!) If a woman is infected, her menstrual blood, vaginal secretions and ejaculate will have the virus in it.

• Cuts or sores on the fingers create risk during vaginal masturbation (fingers or hand in the vagina). Cover hands with latex gloves or buy individual finger cots in the first aid section of most drug stores (they're like little condoms for your fingers). The same applies for buttplay.

• When sex toys are used (such as vibrators or dildos), they should not be shared. Example: Don't remove a dildo from your vagina or rectum and insert it into your partner without first putting a condom on it or disinfecting it with warm water and soap.

• Consensual S&M or rough sex is safe if there is no blood involved. If you are piercing each other, clean the needle with bleach, disinfect the body areas to be pierced with alcohol and wear latex gloves. If shaving the vaginal area, do not share razors.

Dozens and dozens of studies have been conducted on every kind of sex involving men. Now, finally, the CDC has funded a research project on lesbian HIV transmission. The study was launched in May 1999, after another unrelated study, the HIV Epidemiology Research Study of HIV Positive Women (known as HERS), found that 18 percent of the women reported having sex with women. The CDC's project will use virus-matching techniques to identify potential cases of female-to-female transmission.

A second study funded by the National Institutes for Health is also underway. This one examines lesbian injection-drug users to determine if their risk is higher than that of heterosexual female injection-drug users.

Until that data comes in, I hope lesbians and women who sometimes have sex with other women will continue to speak out. Whenever possible and appropriate, be clear with your chosen medical professionals about your risks for transmission of HIV or other sexually transmitted diseases. Lesbians are often the invisible minority in this country. Indeed, research suggests that women who have sex with women are typically reluctant to share this information with their primary physician or gynecologist. Sometimes we have to encourage doctors to ask the right questions and answer our questions, regardless of how much personal squeamishness it may cause us or them.