OBJECTIVE: This study aimed to assess the way women treated for early stage breast cancer perceived the treatment selection process. The purpose was to understand more fully patients' experiences of the decision process and their preferences for participation in treatment decisions. SETTING AND PARTICIPANTS: The study informants were 40 women, treated at a teaching hospital in Sydney Australia, who were interviewed face to face 1 year after their first treatment for stage I or stage II breast cancer. METHODS: This study used a qualitative approach, based on the analysis of interview transcripts. The main areas covered were how the informants' treatment decisions were made and their preferences for participation in treatment decisions. Content and thematic analyses were conducted with findings presented using verbatim quotations for illustration. RESULTS AND CONCLUSIONS: Many of the informants who preferred not to participate in decisions also failed to recognize the need for value judgements (as well as medical expertise) in the decision-making process. Some informants believed they ought to be responsible for the consequences whilst others did not. Difficulties were identified in patient utilization of medical information for treatment decision-making, and also in establishing preferences for the risks and benefits of treatments where few patients had prior experience of the potential outcomes. The findings indicate that patient participation in treatment decision-making is a more complex issue than simply giving patients information and choices. Ways of enhancing patients' involvement in the treatment selection process are discussed.