The Committee noted that the most widely used illicit opioid is heroin, mainly through intravenous injecting. It is estimated that there are 12.6 million injecting drug users (IDUs) worldwide, approximately 10% of HIV infections are associated with injecting drug use. Intravenous drug users are also at a high risk of exposure to hepatitis B and C. Treatment of heroin dependence is therefore of high public health relevance. Both buprenorphine and methadone are effective for the treatment of heroin dependence). However, methadone maintenance therapy at appropriate doses is the most effective in retaining patients in treatment and suppressing heroin use. Methadone is less costly than buprenorphine. It was reported that the cost of buprenorphine per patient per year varied from US$ 300–600 for the generic product to approximately US$ 1750 – 3500 for a branded product in India. The cost of methadone per patient per year in developing countries was reported as US$ 29 for the Slovak Republic, US$ 60 as a generic product from the Netherlands and US$ 180 in the Islamic Republic of Iran. The Committee also noted that misuse of buprenorphine by IDUs is reported from the Islamic Republic of Iran. The Committee noted that there is less clinical experience with buprenorphine than with methadone, but that there is more pharmacological evidence and evidence of favourable societal outcomes. The Committee recommended that the treatment should be initiated and monitored by specially trained staff within an established support structure, but recognized that this would not necessarily require a tertiary hospital setting. Taking into consideration the significant public health need for treatments for opioid dependence, the available evidence on effectiveness and safety of methadone and buprenorphine, the Expert Committee recommended the addition of methadone to the complementary list of the EML for the treatment of opioid dependence with a square box identifying buprenorphine as an alternative.