Cognitive dysfunction, a symptom of schizophrenia, has been recently identified as an important measure of outcome in the treatment of this disorder. Drug-mediated symptom improvement, the traditional measure of treatment success for schizophrenia, typically fails to associate with modifications of cognitive dysfunction, resulting in a failure of the patient to reintegrate into society. A paradigm shift is now required in the conceptualization of treatment success away from symptom decrement and towards treatments that improve cognitive function. Clozapine treatment has been shown to provide a significantly greater improvement in several domains of cognitive function, especially attention and verbal fluency, compared with conventional neuroleptics, whereas risperidone appears to have a beneficial effect on working memory. These results may be because of the normalization of dopamine function by clozapine and antagonism of 5HT2 receptors.