We examine the cognitive ability of 58 demented patients who were evaluated with the Spanish version of the Severe Impairment Battery (SIB). The SIB is composed of multiple simple subtests for memory, language, orientation, attention, visual perception and ability to construct. The battery also assesses social skills, praxis and the ability to respond appropriately to name. The mean SIB scores (72.55 +/- 17.99; range 8-99) correlated with mean scores (10.76 +/- 6.41; range 0-31) on the Spanish version of Folstein's Mini-Mental State Examination (MMSE). The SIB detected deterioration in the nine cognitive areas examined, even in the most severely impaired patients (MMSE = 0-6). These results indicate that the Spanish version of the SIB is a useful instrument for examining severely demented patients.