Cognitive function may be markedly impaired in patients with schizophrenia; however, it has only recently been recognized as an important factor in determining patient outcome. Research has shown that improvements in cognitive functioning occur independently of improvements in positive or negative clinical symptoms, and whereas typical antipsychotics may improve clinical symptoms, they have little or no efficacy in improving cognitive dysfunction. However, there is evidence that the atypical antipsychotic clozapine may improve this core deficit of schizophrenia. This review summarizes 12 published studies that assessed the effect of clozapine on cognitive functioning. As a group, these studies suggest that psychomotor speed, verbal fluency, and verbal learning and memory may be improved by treatment with clozapine. Such cognitive improvements with clozapine treatment may offer an advantage to patients with schizophrenia by enhancing the possibility of better vocational functioning and quality of life.