Complaints on cognitive functioning are often reported in patients suffering from whiplash syndrome, although objective neuropsychological test results do not always support these. In addition, radiological abnormalities and anatomical lesions are found only in a minority of these patients. This has led to a controversy about its existence in the literature. In this systematic review, the results of 22 neuropsychological studies on whiplash were quantitatively analyzed, focusing on working memory, attention, immediate and delayed recall, visuomotor tracking, and cognitive flexibility. Our findings suggest that a consistent overall pattern of cognitive dysfunction can be demonstrated after whiplash injury through neuropsychological testing, both compared to healthy and to asymptomatic controls. Six months after the accident, improvement is found in working memory, attention, immediate recall, and visuomotor tracking. The results are discussed in the light of recent findings on the effect of cerebral dysfunction, malingering, pain-related factors, and the role of coping strategies and posttraumatic stress on neuropsychological test performance. (JINS, 2000, 6, 271–278.)