Aripiprazole is an atypical antipsychotic drug which belongs to the benzisoxazole derivatives. Aripiprazole is available in many salts and polymorphs forms. X-ray diffraction, IR spectroscopy, and DSC could be used for differentiating the polymorphs of aripiprazole. Some instrumental methods of analysis such as UV spectrophotometer, HPTLC, HPLC, and CE can be applied for analyzing aripiprazole and its impurities. Chromatography methods that have an MS/MS detector is the method of choice for analyzing aripiprazole and its metabolites. Bioavailability studies of the polymorphs of aripiprazole and their pharmaceutical preparations are very important to optimize the formulations of the dosage forms.