A multi-state survey of 5663 opioid dependent persons enrolling in 72 methadone maintenance treatment programs (MMTPs) was conducted to determine the prevalence of prescription opioid (PO) abuse, factors associated with PO abuse and sources for POs. Regions where PO abuse was believed to be prevalent were oversampled; primary opioid was defined as the drug used the most before coming to the MMTP. Among primary heroin abusers, 69% reported abusing POs. Opioid abuse frequencies among primary PO abusers were oxycodone (79%), hydrocodone (67%), methadone (40%), morphine (29%), heroin (13%), hydromorphone (16%), fentanyl (9%) and buprenorphine (1%). Correlates (p < or = .01) of PO abuse, using general estimating equations, were: low urbanicity (MMTPs located in comparatively low population density counties), white ethnicity, no history of injecting primary drug, no previous methadone treatment, younger age, chronic pain, and pain as a reason for enrollment. The most frequent sources of POs were dealer, friend or relative, and doctor's prescription; least frequent were Internet and forged prescription. One-third of PO abusers reported a history of injecting their primary drug. PO abuse is highly prevalent among MMTP patients. Future studies should describe HIV/HCV needle injection practices, characteristics that predict treatment outcomes, and factors that contribute to higher prevalence of persistent pain among PO abusers.