Patients with early Alzheimer's disease (AD) were compared to normal controls and patients with early vascular dementia (VaD) on their naming errors using the Boston Naming Test (H. Goodglass & E. Kaplan, 1983). All naming errors were classified into three general error categories: visuoperceptual, semantic, and phonemic. Semantic errors were further classified into coordinate errors (responses that belong to the same semantic category as the target words), superordinate errors (responses that belong to a broader semantic category than the target word), and functional-circumlocutory errors (circumlocutions and responses that functionally describe the target word). The findings indicated that AD participants display more overall naming errors than VaD participants, although the pattern of general errors was similar between the patient groups. However, the qualitative difference between the patient groups was observed within the semantic errors because the AD group made more superordinate errors.