BACKGROUND: Each year, some 25 to 30 inmates in Oslo prisons are transferred to forced isolation in security cells, an often traumatic and degrading experience. MATERIAL AND METHODS: 30 male prisoners who were transferred to security cells were compared to another group of 30 randomised and not secluded inmates who had been referred to the prison psychiatric service. Inmates in the security cell group who previously had been in contact with the prison psychiatric service were compared to those in the same group who had not had such contact. RESULTS: Prisoners in security cells scored higher on restrictions and previous stays in mental hospitals than did non-secluded inmates. Prisoners in security cells who had had previous contact with the prison psychiatric service, had higher negative scores than those without such a contact. Both groups had considerable drug problems. INTERPRETATION: The security cell prisoners are a professional challenge to prison officers and health personnel to who should collaborate on giving the extra attention required to meet their needs.