Functional MR (fMR) imaging techniques have revolutionized the study of psychiatric illness; however, the clinical utility of fMR imaging studies for these disorders is limited. This article addresses the research applications of fMR imaging to the study of psychiatric disorders. The four psychiatric disorders covered in detail include schizophrenia, obsessive-compulsive disorder, Alzheimer's dementia, and substance abuse. Research findings and implications for future study are discussed with reference to both clinical and technological limitations.