Schizophrenia, schizoaffective disorder and bipolar disorder are severe and disabling disorders, associated with marked social or occupational dysfunction, tenfold suicidal risk, intensive healthcare resource utilization and poor prognosis. Atypical antipsychotics developed in the last decade are proving beneficial to a subset of patients. These agents share a reduced risk for EPS and tardive dyskinesia in comparison with first generation antipsychotics. They also appear to improve negative, cognitive, and depressive symptoms while being at least as efficacious as first generation "typical" drugs in controlling positive symptoms of schizophrenia and schizoaffective disorder. Unfortunately, during the late 1990's, case reports and studies began to document a number of adverse events associated with the use of most second generation antipsychotics such as weight gain, hyperlipidemia and hyperglycemia subsumed under the name "metabolic syndrome". Aripiprazole has a unique pharmacological mechanism, making this drug the ideal medication for treatment to patients who experience metabolic syndrome from other second generation antipsychotics. In numerous pervious trials, it has been demonstrated that aripiprazole is a safe and effective treatment for schizophrenia, schizoaffective disorder and bipolar disorder and that it may actually reduce plasma glucose levels and improve lipid profiles, lowering the risk for cardiovascular disease and /or diabetes. Thirty patients with Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) diagnosis of schizophrenia, schizoaffective disorder or bipolar disorder who have experienced a 10 pound increase in weight while on a second generation antipsychotic or hyperlipidemia, or hyperglycemia, will switch to aripiprazole and be monitored for any improvement in BMI, lipids and glucose.