Shewanella (Pseudomonas) putrefaciens is a rare pathogen in humans, and to our knowledge only 13 cases of S. putrefaciens bacteremia have ever been reported in the literature. In this retrospective study we describe 28 cases of S. putrefaciens bacteremia: 16 in premature and 1-day-old neonates, 9 in adults, and 3 in children younger than 1 year of age. All the babies presented with respiratory distress and/or pneumonia. Six of the adults had associated traumatic lesions of the lower extremity, and of the eight patients who died of sepsis, six were neutropenic. Polymicrobial bacteremia was seen in 18 cases. Three syndromes of bacteremic infection with S. putrefaciens appear to exist: the first is associated with prematurity and congenital pneumonia; the second with ulceration of the lower extremities; and the third (which is more fulminant), with an underlying debility. The findings in these 28 cases confirm the fact that S. putrefaciens can invade the bloodstream; however, the presence of concurrent bacteremia makes it difficult to determine the pathogenic role of this organism in septicemia.