The effects of corticosteroids on skeletal muscle is investigated in patients with COLD by electromyography. 8 patients with COLD were treated with 1 mg/kg methylprednisolone in addition to routine O2 therapy and bronchodilators. The electromyographic findings were compared with 13 COLD patients who didn't take corticosteroids. There were no significant difference between the spirometric and arterial blood gases parameters of the two groups. Muscle weakness muscle contractions, reflex abnormalities, myogenous involvement of extremity muscles were more common in the corticosteroid treatment group.