During the years 1966 to 1976, 164 children and adults with pneumococcal meningitis were admitted to our hospital. By 1980,91 of the 111 survivors were assessed with neuropsychological tests to detect cognitive deficits. The 58 adults (age range 18 to 83 years) were divided into groups with and without alternative etiologic factors (mainly head trauma with skull fracture) and compared separately with 141 normal controls. In addition to group comparisons, we made individual assessments of impairment in adults by comparing the observed data with those predicted from regression analysis. The data from 33 children were evaluated without control. In group comparisons, a deficit in the adult group was found in visuomotor speed tests. Individual assessment revealed unequivocal cognitive impairment in three patients.