Although the pathogenesis of Alzheimer's disease (AD) is still not fully understood, it is acknowledged that intervention should be made at the early stage. Therefore, identifying biomarkers for the clinical diagnosis is critical. Metabolomics, a novel "omics", uses methods based on low-molecular-weight molecules, with high-throughput evaluation of a large number of metabolites that may lead to the identification of new disease-specific biomarkers and the elucidation of pathophysiological mechanisms. This review discusses metabolomics investigations of AD and potential future developments in this field.