Gram-negative bacteremia is a common cause of infection in hospitalized patients. Serratia sepsis is known to cause clinically significant morbidity and mortality. The most common species involved is Serratia marcescens. Clinicians have been uncertain as to the role of Serratia odorifera biogroup 1 as a human pathogen because most isolates have not been associated with invasive disease. In previous publications, 12 cases have been described in which S odorifera biogroup 1 caused sepsis. These observations verify the organism's role as a human pathogen.