Over half of the world's estimated opiate users reside in Asia, including an estimated 3.9 million injecting drug users (IDUs). Injection drug use is a significant factor in determining the course of HIV epidemics, particularly during the early stages of epidemics in Asian countries. Several countries report high HIV prevalence in this population and IDUs account for a large proportion of reported infections. The purpose of this review is to examine the current status of the epidemic, the availability and coverage of select interventions recommended by WHO, United Nations Office on Drugs and Crimes (UNODC) and United Nations Joint Programme on HIV/AIDS (UNAIDS), resource requirements for scaling-up harm reduction in Asia, gaps in the national response, barriers to implementation and recommendations for overcoming barriers to scaling up prevention, treatment and care services for IDUs in the region.