HIV is a growing public health threat in Central and Eastern Europe. In Hungary and a number of other countries, men who have sex with men (MSM) account for a high proportion of HIV infections. However, there has been very little systematic study of the sexual risk practices and characteristics of MSM in this region. This study surveyed 469 MSM recruited in Budapest gay community venues in June 2001. Half the men (50%) engaged in unprotected anal intercourse (UAI) in the past 3 months. Of these, 40% of men's insertive and 50% of their receptive acts were unprotected, and 25% had multiple AI partners in the past 3 months. 17% of MSM exchanged sex for money, 26% had female partners in the past year, and condoms were used in only 23% of their vaginal intercourse occasions. Multivariate analyses showed that high-risk behaviour was predicted by not having condoms available when needed, weak risk reduction intentions, negative attitudes toward safer sex, being in a steady relationship, and having a bisexual orientation. Community-based HIV prevention programmes focused on the needs of gay or bisexual men in Central and Eastern Europe are urgently needed.