Linkage between acute coronary syndrome and narcotic drug (cocaine) intake was first described by D. Colleman in 1982. However risk of development of acute myocardial infarction during replacement therapy after opioid withdrawal has not been elucidated. The paper contains description of two cases of development of myocardial infarction in young persons with intact coronary arteries who received synthetic opioid methadone for facilitation of heroine discontinuation. These clinical cases should draw attention of physicians to side effects of the use of methadone for the treatment of heroine addiction.