What is mental illness? It is certainly not a 20th or 21st century phenomenon - accounts of strange behaviour go back to the dawn of civilisation. In this lecture we will explore conceptions of abnormality and the way in which atypical behaviour has been dealt with through history. From trephination to transorbital lobotomy, from hot water baths to cerebral diathermia, we will consider the various 'treatments' employed. We will trace the developments of the asylum from 'Bedlam' to modern psychiatric units and we will examine the pros and cons of the DSM and ICD classification systems. Voices of the antipsychiatry movement - Jacques Lacan, Thomas Szasz, R.D. Laing, Michael Foucault and Erving Goffman - will be aired and their criticisms evaluated in the context of today's 'coporate psychiatry'. With bipolar disorder and schizophrenia as examples, we will conclude by addressing some of the recent research in our understanding of the neurobiological basis of psychiatric disorders and modern concepts such as the endophenotype and transgenerational epigenetics.