Background: We examined the clinicopathologic profile of T1 cancers to determine whether palpable cancers are different from nonpalpable cancers. Methods: A prospective database was reviewed. Palpable TI cancers were compared with nonpalpable TI cancers. Initial significance was determined by chi (2) analysis. Factors found to be significant were then reanalyzed, controlling for tumor size by logistic or linear regression, as appropriate. Results: Of 1263 TI cancers treated between 1981 and 2000, 857 (68%) were palpable and 401 (32%) were nonpalpable. Palpability correlated with pathologic tumor size, mitotic grade, nuclear grade, high S-phase, lymphovascular invasion, nodal positivity, and lack of extensive intraductal component, multifocality, and multicentricity. There was no significant difference in estrogen receptor, progesterone receptor or Her-2/neu status, ploidy, or DNA index. Breast cancer-specific survival was worse for patients with palpable cancers. Conclusions: Palpable cancers are inherently different from nonpalpable cancers, with a less diffuse growth pattern, higher metastatic potential, higher proliferative activity, more nuclear abnormalities, and a worse prognosis.