Prolonged benzodiazepine use is a widespread phenomenon in medical practice. In the present article, we argue that psychological models may contribute to our understanding of benzodiazepine use. This study examined variables derived from the theory of planned behaviour and the health belief model in relation to the length of benzodiazepine use. Data were collected from a sample of all benzodiazepine users with a request for this medicine in the only pharmacy in a Dutch community (N=467). Determinants of the length of benzodiazepine use were analysed separately for inexperienced and experienced users using structural equation modelling (SEM) analyses. For both groups, results showed that the intention to use benzodiazepines was a predictor of length of use. Attitudes towards benzodiazepine use had an indirect influence on length of use, through intentions. Furthermore, a positive attitude toward using benzodiazepines was related to the perceived norm of the prescriber. Experienced users were more inclined to consume benzodiazepines when they had less control over drug taking. In this group, the belief that benzodiazepine use leads to dependence was associated with less control over drug taking and a high intention to use the drug. In addition, older experienced users reported a higher intention to use the drug. For inexperienced users, the perceived attitude of the prescriber towards use of the medicine was a strong determinant. Finally, results of SEM-analyses showed that the model accounted for far more variance in behaviour for experienced users (67%), than for inexperienced users (18%).