Abstract
A fatal case of interstitial pneumonia caused by Mycoplasma pneumoniae with fulminant evolution into diffuse interstitial fibrosis is reported. Treatment with tetracycline and corticosteroids failed to arrest the progress of the disease. Fatal Mycoplasma pneumoniae infections have been reported previously and some degree of pulmonary fibrosis has been described in a few cases but as far as could be ascertained there are no other well-documented cases of diffuse interstitial fibrosis with proved Mycoplasma pneumoniae infection.