Inclusion Criteria:

• Moderate to severe Crohn's disease with 220 < CDAI < 400.
• All patients in the study must have not had any anti-TNF antibodies for at least eight weeks.

Exclusion Criteria:

• Patients will be excluded from the study if they have fulminant Crohn’s disease requiring parenteral steroid treatment, hospitalization, or need of surgery imminently.
• Patients with serious infections in the preceding three months, opportunistic infections within one month, or current signs or symptoms of severe, progressive or uncontrolled renal, hepatic, hematologic, endocrine, pulmonary, cardiac, neurological, or cerebral disease will be excluded.
• Patients will also be excluded from the study if they have a history of a seizure, epilepsy, presumed current central nervous system tumor, have or have had anorexia nervosa or bulimia, are currently taking or have taken in the last four weeks any drug in the monoamine oxidase inhibitor class, or are allergic to Wellbutrin.
• Patients with active major depression or suicidal ideation will be excluded, as will patients with a score of 19 or higher on the Beck depression inventory.
• Patients will be excluded if they are currently or have taken a medicine in the selective serotonin reuptake class, mirtazapine, venlafaxine, a tricyclic antidepressant, a mood stabilizing, or antipsychotic medication in the previous two weeks.
• Patients will be excluded if they are currently abusing alcohol or have alcohol dependence.
• Patients will be excluded from the study if their baseline liver function tests are greater than twice the upper limit of normal, or if a clinical investigator believes that their baseline chemistry, liver function tests or complete blood count contraindicates entry into the study.
• Pregnant or lactating females are excluded.