In order to clarify the significance of subpial beta/A4 peptide deposits (SP beta PD), we examined the brains of 160 consecutive autopsied cases (average age 84.4 +/- 7.7 years) with or without dementia of the Alzheimer type (DAT) pathologically and immunohistochemically. SP beta PD and amyloid angiopathy (AA) showed a significant positive correlation in their severities, both in the DAT and non-DAT groups. AA was present in most cases with SP beta PD, but was absent in all cases without SP beta PD. Our results suggest that SP beta PD and AA would be the related lesions, and that SP beta PD would be formed previous to AA.