The Home Office files of all 295 cases of defendants being found unfit to plead between 1976 and 1988 were evaluated. The majority were male and either schizophrenic or mentally impaired. Median age was 32 years. Two-thirds had past criminal convictions, and nearly 90% had past contact with psychiatric or social services, but only 28% were receiving psychiatric care at the time of their alleged offence; 14% were hospital in-patients. Offences of theft and violence predominated, but in most cases they were not of a serious nature: 34% were rated as mild or nuisance, 40% moderate, and 26% severe. In more than 80% of cases, evidence linking the accused with the offence seemed good. Less than one-third were admitted to special hospitals. Forty-six per cent of the population (135 patients) eventually regained their capacity to plead (within a median of four months), with 76 (26%) returning for trial. Of the remainder, 68 (23%) are still in hospital, 39 of whom have been there for more than five years. Time to discharge without trial reflected the severity of the alleged offence.