This study examined the predictive ability of theory of planned behaviour (TPB) regarding intention to share needles among injection drug users (IDUs). The data were derived from 109 IDUs in Montreal, Canada, and collected by means of self-administered questionnaires. The Spearman's correlation was used to see the relations between the predicting variables and the intention. Furthermore, ordinal regression analysis was conducted to see different predictive possibilities of TPB components. Perceiving needle sharing as a good practice and careless craving for drugs were significantly positively correlated with the intention to share syringe with others in the future 8 months. Ordinal regression results showed that indirect perceived behavioural control as being the strongest predictor of intention. In other words, for every one unit of increase in drug craving behaviour, IDUs are 48% more likely to share their needles in the future 8 months. The results indicate that self-regulatory strategies are important in predicting needle sharing behaviour.