Monkeys with lesions restricted to the inferior parietal lobule or the banks and depths of the superior temporal sulcus were tested on a route-following task. These areas are considered on neuroanatomical grounds to be homologous to parts of the human posterior parietal cortex, where lesions produce profound spatial disorientation. The operated monkeys were impaired on the route task, thus confirming at the behavioural level the anatomical predictions of comparability between parietal cortex in monkey and that in man. The monkeys were not impaired, however, on a visual pattern discrimination or on a visual-spatial task with cue and response separation, a task that was considered on the basis of previous investigations with extensive posterior lesions in the monkey to be sensitive to parietal lesions.