Twenty-three percent of 621 gay men surveyed at three gay bars and one sexual-health clinic in Sydney, Australia, admitted to having unprotected anal sex with casual partners in the first six months of 1998.

The figures were the same for HIV-negative and HIV-positive men.

The research was conducted by Dr. Paul van de Ven, deputy director of Macquarie University's National Centre in HIV Social Research (NCHSR).

A second NCHSR study found that some lesbians also put themselves at risk for HIV by having unsafe sex with gay and bisexual men.

Questioning of 774 mostly lesbian women at the Gay and Lesbian Mardi Gras Fair found that 2 percent of lesbians, 25 percent of bisexual women and 8 percent of heterosexual women had sex with a gay or bisexual man in the preceding six-month period -- and 20 did not use a condom.

"People tend to have sex with people in their friendship group," said NCHSR researcher Dr. Juliet Richter.

And women don't necessarily have sex only within the confines of their stated sexual identity, she said.