The present invention concerns methods and reagents useful in modulating BACE gene expression in a variety of applications, including use in therapeutic, diagnostic, target validation, and genomic discovery applications. Specifically, the invention relates to small nucleic acid molecules, such as short interfering nucleic acid (siNA), short interfering RNA (siRNA), double-stranded RNA (dsRNA), micro-RNA (miRNA), and short hairpin RNA (shRNA) molecules capable of mediating RNA interference (RNAi) against beta-secretase (BACE), amyloid precurson protein (APP), pin-1, presenillin 1 (PS-1) and/or presenillin 2 (PS-2) gene expression and/or activity. The small nucleic acid molecules are useful in the treatment of Alzheimer's disease and any other condition that responds to modulation of BACE, APP, pin-1, PS-1 and/or PS-2 expression or activity.