This report describes the case of a 70-year-old female suffering from diabetes mellitus and dilatative cardiomyopathy with congestive heart failure. It is likely that alveolar-capillary membrane damage occurred apart from cardiac involvement. Diffuse interstitial pulmonary fibrosis subsequently occurred with consequent acute progressive respiratory failure and death. The cause of the damage to the alveolar-capillary membranes is still unknown and we thought that long-term administration of captopril might have contributed to the damage itself, since like all ACE-inhibitors, captopril is able to bring about tissular storage of both bradykinin and prostaglandins and therefore alter the pulmonary reactivity to phlogistic stimuli.