Breast cancer remains the leading cause of death in women aged 30-70 years in the US, and intensive research efforts are focused on combating this disease. As in other areas of the cancer field, the wealth of understanding that has emerged from molecular biology research is starting to impact on diagnosis and treatment of this disease, with trastuzumab ['Herceptin'] a strikingly successful example. At the 91st Annual Meeting of the American Association for Cancer Research [San Francisco, US; April 2000] investigators discussed new approaches that are building on the success of trastuzumab, including attempts to harness HER-2 antibodies to specifically deliver anticancer agents and efforts to develop vaccines against HER-2.