The pharmacology, pharmacokinetics, clinical efficacy, adverse effects, drug interactions, and dosage and administration of aripiprazole are discussed. Aripiprazole is a third-generation antipsychotic agent indicated for use in the treatment of schizophrenia. Unlike other antipsychotics, aripiprazole demonstrates mixed D2 and serotonin (5-HT1A) receptor agonist-antagonist activity that is hypothesized to improve schlzophrenia's positive and negative symptoms; the drug has been referred to as a dopamine-serotonin stabilizer. Aripiprazole is well absorbed, with peak plasma concentrations occurring within three to five hours after administration. The oral availability is 87%. The mean elimination half-life is about 75 hours for aripiprazole and 94 hours for its active metabolite. In controlled, randomized, multicenter trials, aripiprazole has demonstrated efficacy in the treatment of schizophrenia comparable to that of haloperidol and superior to placebo. In a single clinical trial, aripiprazole was superior to placebo in the treatment of acute mania. The most frequent adverse effects are headache, anxiety, insomnia, nausea, vomiting, and lightheadedness. Because aripiprazole is a substrate of both cytochrome P-450 isoenzymes 3A4 and 2D6, there is a potential for other drugs to affect its metabolism. The recommended starting dosage is 10 or 15 mg daily, preferably administered with meals. Aripiprazole offers an alternative to second-generation antipsychotic agents in the treatment of schizophrenia.