A method for extracting ferruginous bodies from sputum and fixed or unfixed lung is described. The principle is to digest the sputum or tissue completely in domestic laundry bleach (5.25% sodium hypochlorite) and to collect the solid residue on a membrane filter. This method allows one to extract from a specimen virtually every ferruginous body that is visible with the light microscope. With this method, ferruginous bodies were found in pulmonary tissue from each of 100 consecutive necropsies of patients 16 years old and over. In one case, ferruginous bodies were found in a concentration of about 750,000 per Gm. of wet fixed pulmonary tissue.