The objective of this study is to compare optimally given methadone maintenance treatment (MMT) for heroin dependence with a novel, sequential strategy, where patients are offered buprenorphine as first line treatment, allowed dose adjustments as needed, and switched to methadone if the maximal dose of buprenorphine is insufficient.

The objective of this study is to compare optimally given methadone maintenance treatment (MMT) for heroin dependence with a novel, sequential strategy (STEP), where patients are offered buprenorphine as first line treatment, allowed dose adjustments as needed, and switched to methadone if the maximal dose of buprenorphine is insufficient.

For this purpose, 96 subjects at two centers (Uppsala and Stockholm) are randomized to MMT or STEP and followed for 6 months. Retention in treatment is the primary outcome. Secondary outcomes in completers are proportion urine samples free of illicit opiates on app. twice weekly sampling, and problem severity as measured by a semistructured interview, the Addiction Severity Index (ASI) at baseline and after 3 and 6 months.

Inclusion Criteria:

• Heroin dependence according to DSM IV > 1year
• Age > 20 years
• Acceptance of the stated treatment principles.

Exclusion Criteria:

• Severe psychiatric illness such as dementia or psychosis compromising the patient's ability to provide informed consent
• Other clinically significant psychiatric illness unless stable under treatment
• Severe medical condition such as advanced lung disease, unstable cardiovascular disease, severe liver disease
• Other clinically significant medical condition unless stable under treatment
• Treatment with anti-seizure drugs or disulfiram
• Pregnancy or intent to become pregnant within the next year
• Ongoing nursing
• Patients involuntarily discharged from a methadone or buprenorphine maintenance program within the last 3 months not eligible.