A significant minority of Australian men who have sex with men (MSM) have never been tested for HIV and many men do not test as often as recommended. Using data from 1770 HIV-negative and untested MSM collected in a national, online survey, we compared men who had never tested for HIV with those who had tested over 12 months ago and men who had tested over 12 months ago with those that had tested in the past year. Two multivariate logistic regression models were constructed. Compared with men tested over 12 months ago, untested men were younger, less educated, less likely to have unprotected anal intercourse with a regular male partner, less likely to have sought advice from a doctor, nurse or community organisation, more likely to expect HIV-negative disclosure, had fewer gay friends and spent more time using social networking websites. Compared with men who had tested over 12 months ago, men who had tested within the last year were younger, more likely to expect HIV-negative disclosure and disclose to casual partners, more likely to have sought advice from a doctor or nurse, had attended gay pools, gyms or beaches and had more gay friends and more male sex partners. Our findings suggest that the Internet and sex education in schools are important ways to promote HIV testing to untested MSM. Testing reinforcement messages delivered through gay community outreach and primary care will reach previously tested MSM.