‘Fuckbuddies’ are a type of regular sexual partner with whom men have ongoing sexual contact, generally in the absence of romantic attachment. We surveyed 989 men who have sex with men (MSM) at the Melbourne Sexual Health Centre, Australia, with the aim of determining the frequency of ‘fuckbuddy’ partnerships among sexual health clinic attendees and assessing their sexual risk. The majority (60%) of 1139 regular partnerships were described as ‘fuckbuddies’. Most MSM (63%) with a ‘fuckbuddy’ had multiple ‘fuckbuddies’. MSM with ‘fuckbuddies’ were more likely to also have casual sexual partners (odds ratio [OR] 5.7; 95% confidence interval 3.6–8.9) and had more casual sexual partners (median of 4 versus 1, p < 0.001) and more rectal chlamydia (12.4% versus 5.7%; adjusted OR 2.3; p < 0.05) than MSM without ‘fuckbuddies’, and this risk persisted after adjusting for total numbers of sexual partners. Our findings suggest that patients with ‘fuckbuddies’ are at particular risk of sexually transmitted infections. We argue that clinicians should specifically ask about ‘fuckbuddy’ partnerships as part of their risk assessment during patient interviews, as these patients may benefit from HIV prevention strategies such as pre-exposure prophylaxis (PrEP).