The memories of 20 patients undergoing elective operations on the heart were assessed by a comprehensive battery of standardized psychometric tests. Testing was conducted 1 to 2 days before, 7 to 10 days after, and 1 month after each operation. Twenty age-matched, healthy control subjects were given the same battery of tests at comparable times. Compared with healthy subjects, the patient group had significantly lower scores on 3 of 19 tests before, 10 of 19 tests 1 week after, and 5 of 19 tests 1 month after surgical intervention. The patient group had similar test performances before and 1 week after the operations and improved on 3 of 19 measures 1 month after the operations. Degrees of illness and cardiopulmonary bypass variables were significantly related to only a small subset of memory measures. Results of this study are consistent with previous reports that underscore the contribution of nonspecific aspects of surgical intervention to neuropsychologic dysfunction in the immediate postoperative period. We conclude that neither the illness nor the surgical variables are directly related to substantial variance in cognitive function after operations on the heart.