The nature and extent of memory deficits were assessed in a group of 27 patients with severe closed head injuries, using tests of learning and immediate memory, together with retention over 30 minutes. The head-injured patients, compared with a normal control group, showed difficulties on all the measures used. Severity of injury was an important determinant of memory performance in older patients but less so in younger. The memory deficit appears to be diffuse in nature, although further work is needed to illuminate the precise nature of the observed deficits.