The goal of this study was to evaluate the effects of the addition of tandospirone, a serotonin-1A (5-HT_1A) agonist, to ongoing treatment with typical antipsychotic drugs, on two cognitive domains that are relevant to functional outcome in patients with schizophrenia. Twenty-six patients with schizophrenia who were receiving stable doses of typical antipsychotics were randomly assigned to adjunctive treatment with 30 mg/day of tandospirone or placebo for 6 weeks. Executive function and verbal memory as well as psychopathology were assessed at baseline and after 6 weeks. Both cognitive measures improved significantly in the patients who received tandospirone; subjects who did not receive tandospirone showed no change. There was no significant change in psychopathology ratings in either group. The results suggest the usefulness of 5-HT_1A agonists for enhancing some types of cognitive performance and possibly social and work function in patients with schizophrenia.