Combining two or more antipsychotics is generally frowned upon, since the utility of this approach is not clear. However, an atypical antipsychotic can sometimes be augmented by a standard antipsychotic drug. The most common example is the combination of clozapine, which has limited D₂ antagonism, and haloperidol or perphenazine. Although few data are available on the efficacy of this approach, some patients appear to benefit. Risperidone combined with a standard antipsychotic resulted in a modest but significant improvement in some patients with chronic schizophrenia studied prospectively (Takahashi et al. 1999). The combination of other atypical antipsychotics and standard antipsychotics may also be warranted if the maximum dosage of the atypical agent has been achieved with less than satisfactory benefit. We tend to prefer the addition of high-potency agents, because the weight gain, hypotensive, and sedation problems associated with the atypical antipsychotics complicate the addition of low-potency agents. Since risperidone is such a potent D₂ antagonist by itself, we push the dosage of risperidone as tolerated by the patient up to 12 mg/day rather than add a standard antipsychotic to it.