The authors assessed the accuracy of published clinical criteria and their own modifications of those criteria in diagnosing Lewy body disease (LBD). Clinical diagnoses were made by two clinicians, blinded to neuropathologic diagnoses, using the Rochester Alzheimer's Disease Center database and traditional medical records. Neuropathologic diagnoses were made according to published guidelines. Results from 21 Alzheimer's disease and 18 LBD patients indicated that no set of clinical criteria was accurate in diagnosing LBD. The only significant predictor of LBD in this population was depression, which was more common in LBD than in Alzheimer's disease. The authors conclude that clinical identification of LBD is an important but unresolved neurological problem.