Cognitive changes in older women receiving chemotherapy are poorly understood. We examined self-reported cognitive function for older women who received adjuvant chemotherapy on Cancer and Leukemia Group B (CALGB) 49907. CALGB 49907 randomized 633 women aged ≥65 with stage I-III breast cancer to standard adjuvant chemotherapy (cyclophosphamide-methotrexate-5-fluorouracil or doxorubicin-cyclophosphamide) versus capecitabine. We examined self-reported cognitive function in 297 women (CALGB 361002) who enrolled on the quality of life substudy and had no gross impairment on cognitive screening. Women were evaluated using an 18-item instrument at six time points (baseline through 24 months). At each time point for each patient, we calculated a cognitive function score (CFS) defined as the mean response of items 1-18 and defined impairment as a score >1.5 standard deviations above the overall average baseline score. Differences in scores by patient characteristics were evaluated using a Kruskal-Wallis test. A linear mixed-effects model was used to assess CFSs by treatment over time. Among 297 women, the median age was 71.5 (range 65-85) and 73 % had performance status of 0. Baseline depression and fatigue were reported in 6 and 14 % of patients, respectively. The average CFS at baseline was 2.08 (corresponding to "normal ability"), and baseline cognitive function did not differ by treatment regimen (p = 0.350). Over 24 months, women reported minimal changes at each time point and insignificant differences by treatment arm were observed. In a healthy group of older women, chemotherapy was not associated with longitudinal changes in self-reported cognitive function.