Nearly 10% of a sample of men charged with a variety of offences claimed amnesia for their offence. The amnesia occurred only among those who had committed violence and was most frequent following homicide. All the amnesics had a psychiatric disorder, four having a primary depressive illness and the remainder being almost equally divided between schizophrenia and alcohol abuse. None of the amnesias had any legal implications. The circumstances of the offences suggested a variety of mechanisms to account for the amnesia, including repression, dissociation and alcoholic black-outs. Psychological defence mechanisms were probably of some importance, even when alcohol was an important factor.