The initiation and maintenance of substantial behaviour change is required to reduce the spread of HIV infection among the intravenous drug-using population. In order to ascertain the efficacy of interventions aimed at reducing HIV-related risk-taking behaviour among this population, valid and reliable (yet preferably short) instruments for measuring such behaviour are required. The HIV risk-taking behaviour scale (HRBS) is a brief 11-item interviewer-administered scale which examines the behaviour of intravenous drug users in relation to both injecting and sexual behaviour. This paper describes the construction of the scale, in addition to data evaluating its reliability and validity. Initial analyses indicate that the scale has satisfactory psychometric properties.