Two groups of 170 left and 173 right brain-damaged patients were given the Raven's Coloured Matrices, in order to study the influence of the hemispheric side of the lesion on this test of visual-spatial intelligence. A significant difference was found between the two hemispheric groups, the right brain-damaged patients scoring worse than the left hemisphere- damaged subjects. Furthermore, patients with right hemispheric lesions showed a striking tendency to neglect the responses lying on the left side of the page, whereas subjects with left hemispheric damage showed only a mild tendency to neglect the alternatives lying on the right half of the sheet. The worse performances obtained on the Coloured Matrices by right brain-damaged patients seemed due for the most part to unilateral spatial neglect. These findings suggest that the bad performances of patients affected by retro-rolandic right hemispheric lesions are not due to a general intellectual impairment, but rather to the detrimental effect of unilateral spatial neglect and of a general disorder in visual-spatial analysis.