Many studies have shown a co-variation of unilateral neglect with nonlateralised attentional functions. Recently, Posner has argued that there are two separate neural systems that influence the posterior attentional system which is presumed to be impaired in unilateral neglect, namely, the posterior system itself (located partly in the inferior parietal lobules) as well as a secondary modulatory sustained attention or vigilance system. This latter system is linked to the nor-epinephrine system, which is known to be more strongly represented in the right compared to the left hemisphere of the brain. If this hypothesis is true, then unilateral neglect should be improved by increasing activation of the sustained attention system. Eight patients suffering from chronic left unilateral neglect were trained to sustain their attention by a self-alerting procedure partially derived from Meichenbaum's self-instructional methods. Using a multiple-baseline-by-function design, as well as multiple-baseline-by-subject designs, statistically significant improvements in unilateral neglect as well in sustained attention were found following onset of sustained attention training, without corresponding improvements in control measures. Theoretical implications for the attentional underpinnings of unilateral neglect are discussed, as well as the rehabilitation implications of this training procedure.