Abstract Sections of area 17 from 9 Alzheimer's disease (AD) and 13 control cases were stained using the monoclonal antibody, Alz-50, which identifies pathologically-involved neuronal systems in AD patients. Strong positive staining was seen only in AD cases. The pattern of staining was highly lamina-selective; laminae I-IVa and V were intensely stained and lamina VI staining was moderately intense, while laminae IVb and IVc were relatively unstained. The results support the growing consensus that cortical pathology in AD is not generalized, but affects specific neuronal populations. The specific anatomical distribution of degenerative change suggests that there may be a specific set of visual deficits in AD patients.