An instrument for measuring patients’ preferences for two identified dimensions of autonomy, their desire to make medical decisions and their desire to be informed, was developed and tested for reliability and validity. The authors found that patients prefer that decisions be made principally by their physicians, not themselves, although they very much want to be informed. There was no correlation between patients’ decision making and information-seeking preferences (r=0.09; p=0.15). For the majority of patients, their desire to make decisions declined as they faced more severe illness. Older patients had less desire than younger patients to make decisions and to be informed (p<0.0001 for each comparison). However, only 19% of the variance among patients for decision making and 12% for information seeking could be accounted for by stepwise regression models using sociodemographic and health status variables as predictors. The conceptual and clinical implications of these findings are discussed. Key words: patient autonomy; decision making; survey research.