A neuropsychological model on how to evaluate patients subjected to stereotactic psychosurgery is presented. Four patients with chronic obsessive compulsive neurosis were randomly assigned to either stereotactic anterior capsulotomy or cingulotomy, and assessed pre-, peri-, and postoperatively according to this model. The best immediate and long-term follow-up results in reducing obsessional symptoms were obtained in the two capsulotomized patients. Psychosurgery should only be performed by a multidisciplinary team of specialists, with objective evaluation, adequate information on patients, and reliable test instruments.