Introduction: The purpose of this study was to determine the increase in diaphragmatic excursion of patients with chronic obstructive pulmonary disease (COPD) treated with theophylline by MR-fluoroscopy which is an innovative method to demonstrate effectiveness of this treatment. Materials and methods: Investigations were performed on a 0.3 T open MR unit. MR-fluoroscopy images of 30 patients with COPD were obtained before and after theophylline treatment. Diaphragmatic movement values were recorded for evaluation. Results: The response of the diaphragmatic movement in COPD patients treated with theophylline was evaluated by MR-fluoroscopy and an increase of 48% in diaphragmatic contractility was determined after the treatment. The increase in contractility was found to be parallel with respiratory function tests and clinical status. Conclusion: Diaphragmatic movement and response to the medical therapy in patients with COPD can be evaluated by MR-fluoroscopy method which can allow accurate measurements. (C) 2003 Published by Elsevier Ireland Ltd.