Background Among gay and bisexual men (GBM), ‘serosorting’ is common and involves restricting sex, or at least condomless sex, to partners of the same HIV status. The prevalence of men conveying their serosorting preferences regarding partners they meet online remains unclear. Methods: This study reviewed 57 178 Australian online profiles obtained directly from a popular gay website. Logistic regression was used to identify factors associated with preferences for meeting HIV-positive partners. Results: Men could indicate their preferences from a list of 22 types of partners; 4358 profiles (7.6%) indicated an interest in meeting HIV-positive men. There were 1959 profiles (3.4%) listing a preference for 21 of the 22 types of men, including 1498 men (2.6%) that specifically excluded HIV-positive men. Men who specifically excluded HIV-positive men on their profiles were younger (mean age 34.7 years), less likely to identify as gay (25.6%) and more likely to always prefer ‘safer sex’ (55.3%) than those who specifically included them (mean age 39.6 years; 62.8% gay-identified; 30.9% preferred safer sex; P < 0.001). Men who specifically excluded HIV-positive partners on their profiles were also more likely to live outside major capital cities (P < 0.001). Conclusions: Being younger, living outside major cities, not identifying as gay, always preferring safer sex and either Caucasian or Asian background were associated with excluding HIV-positive men as potential sex partners. These factors may reflect lower social and community engagement with the gay community. The disinclination to include HIV-positive men as potential sex partners may be due to fear of infection, stigma or poor information about HIV.