In the last ten years advances in analytical methods have enabled the determination of xenobiotics in alternative material such as sweat, saliva, and hair. The aim of this study was to develop an analytical method and measure the concentration of the main opiates in serum saliva and hair of subjects from a detoxification and methadone treatment programme. The analytical strategy in the presented study, based on enzymoimmunoassay screening of opiates in urine and GC/MS confirmation, meets the needs of forensic and clinical toxicology. Blood and saliva samples from thirty seven patients and hair from twenty three with a history of intravenous opiate use were collected for analysis. The ranges of morphine in serum and saliva were 0-2081 and 0-208 ng/ml respectively; corresponding concentrations of codeine were 0-580 and 0-428 ng/ml respectively. The concentration of morphine, codeine and 6-MAM in hair of addicts ranged respectively from 0-32.4, 0-12.5 and 0-2.8 ng/mg. From the clinical toxicology point of view, hair analysis is supplementary to urine, serum or saliva determination, but in drug testing at the workplace it can play a crucial role.