A sample of 90 patients with mild or moderate dementia in Alzheimer's disease was examined for subtypes within the cognitive phenomenology and course of the disorder. Language, memory, praxia, and perception were selected as symptom areas of interest. The distributions of these symptoms and of their relationships as measured cross-sectionally at baseline did not suggest the existence of qualitatively distinct groups. The progression of cognitive impairment during the first 12 months of longitudinal observation provided no evidence of quantitative subtypes. The study confirms the marked interindividual variation in the cognitive phenomenology and course of Alzheimer's disease. It demonstrates, however, the continuous nature of this variation and its unrelatedness to age at onset or familial aggregation.