Evidence for a major involvement of the frontal cortex in various aspects of the temporal organization of memory has emerged from the study of patients who had sustained a unilateral frontal- or temporal-lobe excision for the control of cerebral seizures. It has now been established that the frontal cortex participates in judgements of the temporal order of recent events and of their frequency of occurrence, as well as in the planning and monitoring of the execution of self-determined sequences of responses. Some differential effects related to the side of the lesion were observed, these depending both on the nature of the stimulus material used and on the special demands of the task.