Among 114 breast cancers in Taiwan, the prevalence of p53 mutation (22.8%) and p53 accumulation (38.3%) was similar to that in high-incidence areas. However, novel patterns of p53 abnormalities, including unique sites or types of mutation (i.e. an excessive proportion of G:C to A:T transition at CpG site), and accumulation of wild-type p53 either within nuclear or cytoplasmic compartments were noted. These may have relevance to breast cancer in Taiwan, a low-incidence area.