background Detained women form only a small part of the prison population (in the Netherlands 5%), and research on the mental state of female inmates is scarce.
aim To study the mental condition of female inmates who have been staying on the individual care unit of the penal system since 1994 till 2001. 
method Of this subgroup of detained women judicial and demographic data have been collected, as well as information about their treatment history for mental problems. Examination has been done by a psychologist and/or a psychiatrist.
results The prevalence of mental disorders was high. Of the studied population 65% had at least 1 axis i disorder. In over 80% of the women 1 or more personality disorders were present, while 60% had 1 or more disorders on both axis i and axis ii. There was a striking prevalence of cluster b personality disorder.
conclusion A significant part of this selected population suffers from mental disorders and comorbidity. Further research on the mental health of female detainees is necessary.