The typical antipsychotics (such as haloperidol and chlorpromazine) ameliorate acute episodes and possibly prevent or decrease the risk of occurrence of new episodes, but they have minimal effectiveness against negative symptoms, mood symptoms, and cognitive impairment, which often lead to poor social functioning. Its full Dopamine antagonism is often associated with a number of well-recognized debilitating side effects. One example is EPS. A new class of antipsychotics, the atypical agents (such as clozapine, risperidone, olanzapine), became available starting in the late-1980s. Their mode of action affects both the serotonin and dopamine (DA) receptors. They are better tolerated than the typical antipsychotics with regard to EPS, except at higher doses. The improvement in the side effect profile seen with the atypical antipsychotics is accompanied by efficacy against positive symptoms and perhaps some improvement in efficacy against negative symptoms. Although they offer better efficacy and lower rates of EPS compared to typical agents, they are associated with other side effects that may be of clinical concern. For example, olanzapine and clozapine have an increased incidence of weight gain and diabetes mellitus, risperidone is associated with hyperprolactinemia, and ziprasidone is associated with ECG QT interval prolongation. In addition to tolerability issues, a significant proportion of patients still do not adequately respond to these newer agents. A need still exists for efficacious alternatives that demonstrate improved tolerability and side effect profiles so as to enhance treatment compliance and long-term functioning.