Background In the present study, two epidemic episodes of extended spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae in the neonatal intensive care unit (NICU) were evaluated. Methods Routine and surveillance culture samples were taken from seven neonates with signs of infection in the NICU of Selcuk University Faculty of Medicine between 10 March and 25 April 2011, and between 11 June and 30 September 2011. Results ESBL-producing K. pneumoniae strains were isolated in six different samples (one wound, one blood, and four cerebrospinal fluid cultures) of the three neonates in the first episode and in 11 different samples (seven blood and four cerebrospinal fluid cultures) of the four neonates in the second episode. ESBL-producing K. pneumoniae was isolated from inguinal, axillar region, and stool samples of the nine colonized neonates in the second episode. It was determined on pulse field gel electrophoresis that all strains originated from two clones. Conclusions The deficiencies in the infection control measures in an NICU may transform into an epidemic rapidly. Therefore, periodic training, observation, and monitoring of compliance are important. © 2013 The Authors. Pediatrics International © 2013 Japan Pediatric Society.