OBJECTIVE: The purpose of this study was to determine whether lack of awareness of motor dysfunction and lack of insight into mental dysfunction are related and to evaluate the longitudinal stability of lack of awareness of abnormal movements in schizophrenia. METHOD: Forty-three patients with schizophrenia and tardive dyskinesia participated in the study. The Scale of Unawareness of Mental Disorder was used to assess insight. All patients still meeting inclusion criteria after 2 years (N=16) were reevaluated at follow-up. RESULTS: Twenty (46.5%) of the 43 patients had at least moderate unawareness of their tardive dyskinesia. Awareness of tardive dyskinesia was only modestly related to two of the five dimensions of insight into mental disorder assessed. Patients with the deficit syndrome showed significantly less awareness of their tardive dyskinesia than patients without the deficit syndrome. Lack of awareness of tardive dyskinesia was stable over time. CONCLUSIONS: Lack of awareness of tardive dyskinesia is a common feature in schizophrenia and is stable over time. Since patients are often unaware of dyskinesia, direct clinical examination is required to identify early tardive dyskinesia.