The purpose of this study was to examine the nature and potential effects of disclosure patterns and unsupportive social interactions in breast cancer patients. Disclosure, the thoughts and feelings people communicate to others, and unsupportive social interactions, the upsetting or unsupportive responses people receive from others, have been infrequently studied in breast cancer patients. Sixty-six early stage breast cancer patients diagnosed less than one year completed a written questionnaire. Results indicated that the women reported confiding in family and friends more than in mental health workers. Fears of recurrence and worries about the effects of the illness on family members were the most important concerns, whereas concerns about body image were the least troublesome. Failure to disclose concerns was associated with low social support, high unsupportive social interactions, and low emotional well-being. Most of the unsupportive responses received from other people were either behaviors of minimizing or distancing. Unsupportive reactions were significantly associated with greater role limitations due to emotional problems and decreased social functioning. Implications for interventions and future research are discussed. Copyright © 2003 John Wiley & Sons, Ltd.