A study to investigate the process by which ABT-126 is absorbed, distributed, metabolized and eliminated by the body of stable schizophrenic volunteers receiving treatment with an atypical antipsychotic.

Inclusion Criteria:

• Subject has signed informed consent;
• Current diagnosis of schizophrenia;
• Clinically stable on the same single second-generation (atypical) antipsychotic for the past 8 weeks;
• Meets study-specific criteria for Positive and Negative Syndrome Scale (PANSS);
• Females are not pregnant, not breast-feeding;
• Females are post-menopausal or surgically sterile or practicing birth control;
• Males are surgically sterile or agree to be sexually inactive or use barrier method of birth control

Exclusion Criteria:

• Diagnosis of schizoaffective disorder;
• Diagnosis with mental retardation;
• Subject has a substance dependence disorder that has not been in sustained remission for at least 1 year;
• Acute psychosis hospitalization within past 6 months;
• Bipolar disorder, manic episode, dementia, obsessive-compulsive disorder, or drug-induced psychosis or current major depressive disorder;
• Current clozapine treatment;
• Suicidal ideation or behavior;
• BMI of 39 or greater;
• Relevant drug sensitivity or allergy;
• Positive hepatitis or HIV test result; positive urine screen for drugs of abuse or alcohol;
• Recent clinically significant illness/infection or surgery;
• Recent blood product transfusion, donation or loss of 5 mL/kg of blood;