Simple alerted auditory reaction time (SRT) behavior with various foreperiods was investigated in a group of long-term survivors of childhood ALL who were in continuous first remission. As part of therapy, the patients had received cranial irradiation and intrathecal chemotherapy to prevent the development of central nervous system leukemia. The patients were divided into three groups on the basis of CT brain scan findings: (1) those with normal CT scans (n = 10); (2) those with evidence of cortical atrophy (n = 8), and (3) those with intracerebral calcifications (n = 5). The SRT results indicated significant differences between patients with normal and abnormal CT scans. Specifically, patients with abnormal scans reacted slower, and this latency was exaggerated by increasing the length of the warning interval. Furthermore, they reacted with larger variability which increased with the prolongation of testing. Moreover, the severity of impairment was related to the type of CT-scan abnormality: patients with calcifications performed more poorly than patients with evidence of atrophy. The present results revealed a strong correlation between the presence and type of CT-scan abnormalities and attentional performance in long-term survivors of childhood ALL.