The London Patient Choice Project (LPCP) was established to offer NHS patients more choice over where and when they receive treatment, and to reduce waiting times. The LPCP offered those patients waiting around 6 months for elective procedures a choice of treatment at an alternative NHS or private hospital, or treatment at an overseas hospital.The aim of this article is to investigate the following questions regarding patients' response to choice: (a) What are the factors that patients consider when deciding whether to accept the alternatives they are offered? (b) What is the relative importance to patients of each factor when making their choices, i.e. what trade-offs are patients prepared to make between time waited and other factors? (c) Are there any systematic differences between subgroups of patients (in terms of their personal, health and sociodemographic characteristics) in their response to choice?Patients' preferences were elicited using a discrete choice experiment. Patients eligible to participate in the LPCP were recruited prior to being offered their choice between hospitals and each presented with seven hypothetical choices via a self-completed questionnaire. Data were received from 2114 patients. Thirty percent of respondents consistently chose their 'current' over the 'alternative' hospital. All the attributes and levels examined in the experiment were found to exhibit a significant influence on patients' likelihood of opting for an alternative provider, in the expected direction. Age, education and income had an important effect on the 'uptake' of choice. Our results suggest several important implications for policy. First, there may be equity concerns arising from some patient subgroups being more predisposed to accept choice. Second, although reduced waiting time is important to most patients, it is not all that matters. For example, the reputation of the proffered alternatives is of key importance, suggesting careful thought is required about what information on quality and reputation can/should be made available and how it should be made available to facilitate informed choice.