Objective Internet sex-seeking is common among young men who have sex with men (MSM). However, research examining its association with risky sexual behaviour has produced mixed findings, possibly due to various operational definitions of internet sex-seeking which fail to account for its multi-dimensionality. This study purposed to: (1) examine if the way internet sex-seeking behaviour is operationalised influences its association with risky sexual behaviour (unprotected anal intercourse (UAI) and casual sex) and (2) determine the association of each operational definition with sexual risk.

Methods We recruited 263 sexually-experienced young MSM (18–29 years) and operationalised internet sex-seeking behaviour in four ways: (i) ever used the internet to meet other men, (ii) currently own a profile on a website dedicated to meeting other men, (iii) ever physically met a man you initially met online and (iv) ever had sex with a man you met online. Using binomial regression, we examined the association of each operationalisation with UAI and casual sex.

Results Only MSM who reported physically meeting a man they met online and those who ever had sex with a man they met online were more likely to report a history of UAI (p<0.05), while MSM who engaged in all forms of internet sex-seeking were more likely to engage in casual sex (p<0.05). However, the strength of these associations varied according to the mode of operationalisation.

Conclusions The way internet sex-seeking is operationalised in research is differentially associated with sexual risk. Against this backdrop, the utility of these operational definitions in future research and inferences drawn from such research must be interpreted with caution. Findings have important implications for sexual health research and methodology, survey development, sexual health prevention interventions, and evaluating sexual risk among young MSM.