Background:Gay and bisexual men experience a disproportionate burden of ill health compared with the general male population. However, little is known regarding health inequalities that exist within this group. We describe five key physical health indicators and their variation across common axes of inequality. Methods:Community-based opportunistic sampling recruited 5799 gay and bisexual men to a self-completion Internet survey. Respondents provided data relating to their height, weight, physical activity and substance use (tobacco, alcohol, illicit drugs). Responses were compared across seven demographic characteristics. Results:Indicators of problematic health behaviour were concentrated within different groups and inequalities were rarely observed in the same direction. Older men were more likely to be overweight and drink alcohol frequently but less likely to smoke or use illicit drugs. Men of Asian ethnicity were more likely to exercise infrequently but less likely to smoke. Men living in London were more likely to smoke and use illicit drugs but less likely to be overweight. However, lower education was associated with being overweight, frequent alcohol, low exercise and smoking. Conclusion:There is evidence of significant demographic variation in physical health-related behaviours among gay and bisexual men, and men with lower levels of education are consistently in greater need.