Attentional fatigue usually follows intense use of mental effort and is manifested as a decreased capacity to concentrate, that is, to direct attention. The purpose of this study was to examine the capacity to direct attention in persons with cancer during the initial phase of illness. The sample consisted of 32 women without cognitive or affective disorders who underwent surgery for localized (Stage I or II) breast cancer. Subjects manifested attentional deficits of varying intensity on a battery of tests of directed attention on the day before discharge from the hospital, which was a mean of 3 days following mastectomy or breast conservation surgery. Unexpectedly, the two surgical groups did not differ significantly in attentional capacity and functioning. Attentional test scores were not significantly correlated with narcotic pain medication interval, mood state, or self-ratings of attentional functioning. However, as number of days postsurgery increased, attentional performance decreased. The theoretical basis for further examination of attentional fatigue in people with cancer or other life-threatening illnesses is discussed.