Provided herein are peptides having dual-site BACE1 inhibitory activity, useful for the treatment of, for example Alzheimer's disease and diabetes. One such peptide is a dual-site BACE1 inhibitor, or a pharmaceutically acceptable salt thereof, binding to both an enzymatic active site and an catalytic domain of the BACE enzyme, and an exosite inhibitory part is connected to an active-site inhibitory part of the dual site BACE1 inhibitor by a linker.