Self-reported use of gamma-hydroxybutyrate (GHB) among clubbers has increased over the last decade, and is often reported in the scientific literature in association with negative events such as amnesia, overdose, and use in drug facilitated sexual assault. However, there has been relatively little work investigating the phenomenology of GHB intoxication, and the reasons underlying use. In this study, 189 individuals reporting at least one lifetime use of GHB completed an online questionnaire recording GHB use behaviours, GHB use function, and subjective GHB effects. The most frequently reported primary GHB use functions were for recreation (but not in nightclubs) (18.3%); to enhance sex (18.3%); to be sociable (13.1%); and to explore altered states of consciousness (13.1%). GHB was more commonly used within the home (67%) compared to nightlife environments (26.1%) such as clubs, although this differed on the basis of respondent's sexuality. Principle components analysis of GHB user responses to the subjective questionnaire revealed six components: general intoxication effects, positive intoxication effects, negative intoxication effects, negative physiological effects, positive sexual effects and negative sexual effects. Component scores predicted function of use.