Inclusion Criteria:

1. DSM-IV (Diagnostic and Statistical Manual of the American Psychiatric Association) diagnosis of current opiate dependence.
2. Individuals seeking opiate-substitution pharmacotherapy for opiate dependence.
3. Males and non-pregnant, non-nursing females, 18 to 59 years of age (inclusive).
4. Individuals able to give informed consent and willing to comply with all study procedures (e.g., providing of urine samples under observation, completing questionnaires).

Exclusion Criteria:

1. Any acute or chronic medical condition that would make participation in the study medically hazardous (e.g., acute hepatitis, unstable cardiovascular, hepatic, or renal disease, unstable diabetes, symptomatic AIDS; not HIV-seropositivity alone).
2. Aspartate or alanine aminotransferase (AST, ALT) levels greater than three times the upper limit of normal.
3. Individuals currently taking systemic anti-retroviral or anti-fungal therapy.
4. Current dependence (by DSM-IV criteria) on any psychoactive substance other than opiates, caffeine, or nicotine.
5. Current, primary, Axis I psychiatric diagnosis other than opiate, caffeine, or nicotine dependence.

6. Females of childbearing potential who do not agree to use a medically acceptable method of birth control. Acceptable methods include

   1. oral contraceptive,
   2. barrier (diaphragm or condom) - a spermicide is not required due to the possibility of local irritation and allergic type reactions, but are recommended for use,
   3. levonorgestrel implant,
   4. intrauterine progesterone contraceptive system,
   5. medroxyprogesterone acetate contraceptive injection, or
   6. complete abstinence.
7. Enrollment in an opiate-substitution (i.e., methadone, levo-alpha-acetylmethadol) treatment program within 45 days of enrolling in the present study.
8. Individuals having taken (licitly or illicitly) LAAM, methadone, or naltrexone within days of enrolling in the present study.
9. Individuals having taken buprenorphine, other than as an analgesic, within 365 days of enrolling in the present study.
10. Participation in an investigational drug or device study within 45 days of enrolling in the present study.
11. Anyone, who in the opinion of site principal investigator, would not be expected to complete the first phase of the study protocol (e.g., due to pending incarceration or probable relocation from the clinic area).