This study examines the nature and extent of perseveration in 15 individuals with closed-head injury (CHI) by (a) identifying and describing the types of perseveration that occurred on verbal and non-verbal tasks, (b) examining the possible underlying neuropsychological mechanisms of perseverative behaviour and (c) exploring neuroanatomical correlates of perseveration. Performance of the 15 CHI patients was compared with 15 neurologically normal subjects matched for sex, age, handedness and educational level. The CHI subjects produced significantly more perseverations than did normals, and 'recurrent' perseveration was the most frequently occurring type. A test of verbal learning elicited the greatest number of recurrent perseverations. Overall test performance of the CHI group suggested that memory dysfunction and impaired attention were most likely responsible for perseverative errors. CT scan analyses showed that the three most perseverative CHI subjects evidenced left temporal lobe damage.