A pharmaceutical composition, or pharmaceutical agent for treating A.beta. amyloidosis in a patient that has at least one laminin-derived peptide or fragment thereof from the group D-A13, D-HA3G76, D-A4G82, D-A5G81, D-A5G101, D-HA3G47, D-HA3G58, D-HA3G74, D-HA3G83, D-A5G82, D-R-AG73, D-R-A13, D-R-HA3G76, D-R-A4G82, and D-R-A5G81.