Alzheimer's disease accounts for the majority of dementia in the elderly. Worldwide, approximately 20 million people are suffering from this devastating disease, with no effective treatment currently available. For efficient drug design, it is important to identify the molecular mechanisms underlying the pathology of the disease. An invariant feature in the pathology of Alzheimer's disease is the amyloid-beta peptide. Amyloid-beta is produced by endoproteolytic cleavage of the amyloid precursor protein by beta- and gamma-secretase. In the past 2 years, the protein responsible for beta-secretase activity has been isolated and researchers are close to identifying gamma-secretase. These recent achievements in Alzheimer's disease research have provided helpful tools for the development of therapeutics.