Objectives Access to healthcare in most western societies is based on equality. Rapidly rising costs have fuelled debates about differentiation in access to healthcare. We assessed the public's perceptions and attitudes about differentiation in healthcare according to lifestyle behaviour. Methods A vignette study was undertaken in participants in a colorectal cancer screening pilot programme in the Netherlands. Screenees with a negative test result received a questionnaire in which nine hypothetical situations were described: three different healthcare settings (screening, lung cancer, chronic (...) obstructive pulmonary disease) combined with three forms of differentiation each: a difference in premium, waiting list ordering or copayment according to lifestyle. We evaluated the responses using a general hierarchical linear model. Results The percentage of participants in agreement with differentiation varied from 20% to 58% (overall mean of 40%). Significantly more participants were in favour of giving a premium discount to those who do not engage in unhealthy behaviour compared with supporters for higher payments for those who do. More differentiation was supported for non-smoking versus smoking cessation than for participation versus non-participation in screening. We observed in-group favouritism in smokers, but no significant effects of age or disease. There was no support for waiting list ordering based on lifestyle. Conclusions Results of this study show that Dutch citizens eligible for colorectal cancer screening are in favour of some form of financial differentiation in the distribution of healthcare, but that significant differences exist between type of setting and the type of behaviour. Our study can be used in the ongoing discussion about solidarity and behaviour in healthcare. (shrink)