Patients with Huntington's disease (HD), alcoholic Korsakoff's syndrome (KS), and Alzheimer's disease (AD) were compared with normal control subjects on a task designed to assess recognition memory for different classes of stimuli: spatial, verbal, color, pattern, and facial. In addition, recall of verbal stimuli was assessed at two delay intervals. On recognition testing, AD and KS patients were impaired on each of the five stimulus conditions. However, HD patients, though impaired on four of the recognition conditions, were unimpaired when verbal stimuli were used. On recall testing, the AD, HD, and KS groups were equally impaired at the shorter delay (15 s). However, at the longer delay (two minutes), the KS and HD patients, though still impaired relative to the normal control group, performed significantly better than the AD group.