The total number of psychiatric inpatients admitted to National Taiwan University hospital from 1972 to 1982 is 1768, of which 95 (5.7%) are multiple admission. Diagnostic changes occur in 15 of the 95 patients, that is 15.8%. According to original diagnoses, these 15 cases may be divided into four groups. In Group A, 5 were schizophrenia, of which 4 were re-diagnosed to be manic-depressive psychosis (MDP), and 1 to be atypical psychosis. In Group B, 3 were MDP, 2 of which became schizophrenia, and 1 atypical psychosis. Group C had 2 neurosis cases, which were changed to schizophrenia and MDP. In Group D, 5 received the diagnosis of ”other psychosis,” of which 2 turned out to be schizophrenia, 2 MDP, and 1 paranoid state. Upon close clinic analysis, five major causes for the alteration in diagnosis were found.1. Subject: A case may have multiple illnesses, the fact that complicates diagnosis.2. Information: The psychopathology does not have wide enough coverage to include multiple factors such as affect, behavior, cognition, and drive.3. Observation: The description in the case records is often imprecise.4. Time: Apparently too much emphasis was placed on the cross-section changes and not enough on the changes in clinical course.5. Criteria: An over-emphasis on thought disorder often led to inaccurate diagnosis.