Staphylococcus lugdunensis is one of coagulase-negative staphylococci, but rarely causes aggressive and progressive infections similar to Staphylococcus aureus infection. Moreover, agglutination test for clumping factor can be positive, and the colony morphology often resembles that of S. aureus, but S. lugdunensis is usually sensitive to all antimicrobials used against staphylococci. We report a case of septicemia caused by S. lugdunensis in a 71-year-old man with diarrhea, diabetes mellitus, and peripheral neuropathy. (Korean J Clin Microbiol 2007;10:70-72)