We interviewed 419 adult women in Minnesota, who were selected at random and without a history of breast cancer, to ascertain what percentage could correctly report that cure was the same for breast conservation therapy and mastectomy, what percentage would state a preference for breast conservation therapy rather than mastectomy, and characteristics associated with these outcomes. Nearly all women (n = 360; 86%) had heard of both mastectomy and breast conservation therapy; among these women, 37% correctly reported that the two treatments were equally efficacious. Given a scenario where they were diagnosed with breast cancer amenable to either treatment, 58% of participants stated a preference for breast conservation therapy. Older women were less likely than younger women to know that cure was the same for breast conservation therapy and mastectomy (adjusted OR = 0.5, 95% CI 0.2, 1.0), and women residing in urban areas were more likely to prefer breast conservation therapy over mastectomy compared to rural residents (adjusted OR = 2.2, 95% CI 1.3, 3.8). Comparing these findings to women diagnosed with breast cancer in Minnesota, breast conservation therapy was found to be performed less frequently than preference for such therapy among women in our study would suggest. Educating women prior to diagnosis about breast cancer treatment options, and exploring reasons for the gap between actual utilization of breast conservation therapy and prediagnosis preference, may be indicated. Copyright (C) 2000 Elsevier Science Inc.