Current health care policies advocate patient participation in treatment decision making. Little evidence on possible differences between European women's preferences for involvement in this process exists. In this study we explore preferences for involvement in treatment decision making in 15 European countries in a sample of 9434 women seeking treatment for urinary incontinence in an outpatient setting. Their generally preferred role in treatment decisions was assessed using the Control Preferences Scale. Results show variations within and between countries in preferences for involvement in treatment decision making. The 'collaborative role' was the most preferred role in Austria, Belgium, Denmark, France, Germany, Ireland, Sweden, Switzerland, the Netherlands and the UK. In Greece, Portugal and Spain the 'passive role' was most preferred. Over a third of women in Denmark, Finland and Norway preferred an 'active role'. Multinominal regression analyses found that, after adjusting for case mix and factors previously associated with role preferences, country membership was strongly associated with role preferences, with women living in Southern European countries preferring a more passive role. Such clear differences are of interest in the current health care environment where active patient participation is being encouraged. Greater efforts need to be made to establish whether patient preferences are genuine or merely a learned response influenced by cultural attitudes and traditions so that a balance can be struck between assisting women to play a more active role in the treatment decision-making process without disregarding some women's genuine preferences to play a more passive role.