The results of methadone concentrations in plasma in selected group of 13 patients (1 female, mean age 25.7 years SD ± 5.0; from 19 to 42 years) from methadone maintenance treatment program were basis for further discussion. Methadone do se was 104 mg on an average (SD ± 53; 40 – 170), and mean through concentration of methadone was 300.6 ng/ml (SD ± 167; 85 – 616) in the group. The clinical relevance of the findings with references from the literature was discussed. It was concluded that there has not been detected till now any fixed formula, which might be used to calculate optima! methadone dose on the basis of its plasma concentration.

Key words: methadone plasma concentration – methadone maintenance treatment – methadone plasma levels