Patients diagnosed as having mild or moderate primary degenerative dementia of the Alzheimer's type (PDDAT), and normal elderly subjects were tested for spatial order and a spatial recognition memory. Results for spatial order memory indicated that compared to normal elderly subjects, patients with mild PDDAT showed an impaired memory only for the last serial positions. In contrast, with respect to spatial recognition memory, patients with mild PDDAT showed an impaired memory only for the early serial positions. Patients with moderate PDDAT were impaired on all serial positions for both spatial order and spatial recognition memory. Based on comparable deficit patterns seen in animals and patients with hippocampal and parietal cortex lesions, it is suggested that memory deficits displayed by PDDAT patients might be a function of underlying pathology in the hippocampus and parietal cortex.