Serratia marcescens is a nonsporulating, Gram-negative, actively motile rod which produces a bright red pigment on most laboratory media. It is generally thought to be a saprophyte found in the soil and does not grow easily at 37 C or occur in man or animals naturally.1 The literature concerning the recovery of Serratia marcescens from clinical specimens in man, and from animals, has been reviewed by Fulton, Forney, and Leifson.2 Serratia has been associated with meningitis, fatal endocarditis, fatal septicemia, otitis media, sinusitis, respiratory infections, bronchiectasis, urinary infections, and also infant diarrhea. Papapanigiotou and Aligizakis3 reported recovery of S. marcescens from an empyema cavity following thoracoscopy and intercostal drainage. Gale and Lord4 and Robinson and Wooley5 reported pseudohemoptysis due to the red pigment of this organism and not to the presence of blood in sputum specimens. Rabinowitz and Schiffrin6 described contamination of a ward