Forty-eight patients with mild to moderate dementia of Alzheimer's type (DAT) were tested with a generative associative naming task, a task that combines the aspects of fluency and of word association tests. The variables taken into consideration were the number of adequate and inadequate responses, conventionality, word frequency and lexical-semantic relation to the target. DAT patients' performances were compared to those of a group of control subjects matched for sex, age and educational level. As a group, the patients gave fewer adequate responses, more idiosyncratic responses and perseverations, while there was no difference in the qualitative variables. However, the analyses of the performance profiles suggest that, irrespective of the severity of the disease, two major subgroups of DAT patients may be identified: (1) a first subgroup of subjects produced words with a lower conventionality rate and these were mostly in propositional relationship to the target; they also produced a higher rate of idiosyncratic responses and perseverations. (2) A second subgroup of subjects gave more conventional responses, mostly in the hierarchical-categorical relationship. The disorders of the former subgroup seem to correspond to a disrupted access to some relatively spared semantic abilities, whereas those of the latter to a semantic breakdown.