Criminality in patients with mental retardation is not rare. It has also many particularities. the aim of this study was to describe the socio-demographic and criminal characteristics in patients with mental retardation in order to identify preventive measures that could have been applied.

This is a retrospective and descriptive study including patients with mental retardation in forensic psychiatry in RAZI hospital after legal irresponsibility by reason of dementia as defined in the Tunisian Penal Code. the collection of informations was conducted using epidemiological Fact Sheet including socio-demographic, clinical and criminological data.

Our population had an average age of 29. Near the 2 / 3 of patients lived in urban or suburban areas. the socio-economic status was poor in more than 60% of cases. Most of our population was single and illiterate. One third had a history of seizures.

Mild mental retardation was present in more than half of cases. Crimes against property were most observed followed by the assault and homicide. Nearly half of the patients committed their crime within a group, without premeditation. Patients with a mild mental retardation committed more crimes against property while those with average or deep retardation did more crimes against persons. This difference is not statistically significant.

Identification of the socio-demographic, clinical and criminological profile of patients with mental retardation and determination of risk factors of violence allows a better care and prevention of violent conduct.