Staphylococcus lugdunensis is a member of the coagulase negative staphylococci (CoNS) which has been associated with serious infections in humans. Species identification of S. lugdunensis isolates should be done but they may be misidentified as other CoNS species or Staphylococcus aureus due to positivity for clumping factor. We report the first two cases of catalase-positive and Gram positive cocci isolated from blood and venous catheter, which were positive for latex agglutination coagulase test but susceptible to penicillin, negative for tube coagulase test and negative acid production from mannitol and finally identified as S. lugdunensis. (Korean J Clin Microbiol 2004;7(1)90-93)