Inclusion Criteria:

   - outpatient age 18 through 55 inclusive

   - meets DSM-IV criteria for obsessive-compulsive disorder (OCD) with Yale-Brown
   Obsessive-Compulsive Scale (YBOCS) score greater than or equal to 20

   - provides written informed consent

   - has taken for at least 12 weeks at least the dose shown of a selective serotonin
   reuptake inhibitor (SSRI) [citalopram, escitalopram, or fluoxetine 20 mg/d; paroxetine
   40 mg/d; sertraline 50 mg/d]; or venlafaxine 225 mg/d; or duloxetine 60 mg/d.

   - if taking buspar, gabapentin, an atypical antipsychotic, or a benzodiazepine, dose has
   been stable for 4 weeks

   - has negative urine drug and pregnancy tests

   - is practicing reliable birth control method

   - has blood pressure readings at screening visit that are less than 140 mm Hg systolic
   and 90 mm Hg diastolic,

   - weight is greater than 100 lbs at screen

Exclusion criteria:

   - requires psychotropic medications other than an Serotonin Reuptake Inhibitor (SRI), a
   benzodiazepine, buspirone, an atypical antipsychotic, and/or gabapentin

   - is taking clomipramine

   - is taking fluvoxamine

   - is taking medication that inhibits hepatic enzyme CYP1A2

   - is taking a monoamine oxidase inhibitor

   - has co-morbid tics or Tourette's disorder

   - has hoarding as the primary or only OCD symptom

   - has a history of panic disorder

   - has a history of glaucoma

   - has a history of seizures

   - has a history of schizophrenia or psychotic disorder, or schizotypal personality
   disorder

   - has depression with current suicide risk

   - has mental retardation, pervasive developmental disorder, or cognitive disorder

   - has a factitious disorder

   - has current or past cyclothymic disorder or bipolar disorder

   - has a dissociative disorder

   - has personality disorder sufficient to interfere with study participation

   - has organic mental disorder or dementia

   - has current or past substance abuse / dependence (excluding nicotine)

   - has current or past anorexia or bulimia

   - has serious or unstable medical disorder, including hypertension or cardiac disease

   - has history of myocardial infarction or cardiac arrhythmia

   - has history of or has current diagnosis of hypertension

   - is pregnant or breast-feeding

   - is receiving psychotherapy for OCD

   - is intending to receive psychotherapy for OCD during the study

   - has had a previous trial of d-amphetamine of at least 30 days duration

   - is unable to speak, read, or understand English

   - is not likely to follow study procedures

   - is not suitable for study in the investigator's opinion