This study examines the relationship between self-reported use of opiates and the dose of oral methadone found to be needed on admission to an in-patients drug dependence unit. The sample consisted of all opiate addicts admitted in a 12-month period. For methadone addicts there was a close relationship between the two dose measures: for heroin addicts there was no relationship. Users of illicit heroin who generally state doses in 'grammes', reported a mean daily dose of 312.5 mg, but needed only 43 mg of oral methadone. Mean values for methadone addicts were 56 mg self-reported use, and 49 mg needed on the drug unit. Some of the reasons for the discrepancy in the two doses for the heroin addicts are discussed and clinical implications with regard to prescribing for opiate addicts are drawn.