Women with breast cancer frequently report cognitive problems to healthcare providers during and after adjuvant therapy. Patients' perceptions of their cognitive problems would be expected to relate to objectively measured cognitive impairments. We explored the relationship between perceived cognitive function and objective ratings of thinking ability in early-stage breast cancer patients receiving hormonal therapy. In particular, we targeted objective measures of learning and memory as the primary endpoints in this exploratory study. We included a comprehensive battery of objective measures of cognitive function to explore relationships between perceived cognitive problems and impairments in other domains of cognitive function. At a minimum, our results indicated that women's complaints of cognitive problems should prompt additional assessment to clarify the bases of the problem and initiate appropriate intervention.