OBJECTIVES: The subject of patient self-determination in health care has gained broad interest because of the increasing number of incompetent patients. In an attempt to solve the problems related to doctors' decision making in such circumstances, advance directives have been developed. The purpose of this study was to examine relationships between public attitudes towards patient autonomy and advance directives. SUBJECTS AND MAIN OUTCOME MEASURES: A stratified random sample of 600 adults in northern Sweden was surveyed by a questionnaire with a response rate of 78.2%. The subjects were asked about their wish for control of their health care, their concerns about health care, their treatment preferences in a life-threatening situation (both reversible and irreversible), and their attitudes towards the application of advance directives. RESULTS: Numerous relationships between various aspects of self-determination in health care (desire for control, fears of over-treatment, and choice of treatment level) in general and advance directives, in particular, were found. Those who wanted to have a say in their health care (about 94%) also mainly supported the use of an advance directive. CONCLUSIONS: The fact that almost 30% of the respondents were undecided concerning their personal use of advance directives points to a lack of knowledge and to the necessity of education of the public on these issues.