Patients who admit to using buprenorphine by the intravenous route will be randomized to either Subutex or Suboxone and be followed up for 3 months to determine if there is less injection with Suboxone than with Subutex based primarily on patient diaries.

Patients randomized to Suboxone may continue to receive the product for a further 9 months at their request and will be monitored at 3 month intervals.

Patients will receive a payment for the inconvenience of keeping a daily diary and to cover their travel expenses.

Inclusion Criteria:

1. Male or female opioid-dependent outpatient aged 18 years or older,
2. Women of childbearing potential must have a negative urine pregnancy test result at the Inclusion Visit (test under supervision of the investigator or designee),
3. Women of childbearing potential must use an effective birth control method. Women of non-childbearing potential must be postmenopausal or must be surgically sterile (hysterectomy and/or bilateral oophorectomy),
4. On buprenorphine (Subutex® or generic buprenorphine) maintenance therapy at a minimum daily dose of 2 mg for at least 3 months prior to inclusion,
5. Declaring buprenorphine intravenous misuse at least four times/week and showing needle marks,
6. Willing to stop or reduce buprenorphine intravenous misuse,
7. Having received oral and written information about the trial, and provided written informed consent prior to admission to this trial.

Exclusion Criteria:

1. Pregnancy or breast-feeding,
2. Contraindication or history of hypersensitivity to buprenorphine, naloxone or to any excipient of Suboxone® or Subutex®,
3. Any medical or psychiatric condition which in the opinion of the investigator would make participation difficult or unsafe,
4. Participating in another trial,
5. Patients in the exclusion period of the "Fichier National des personnes qui se prêtent à des recherches biomédicales" (National Index of persons participating in biomedical researches, or National Index of volunteers).