Klebsiella pneumoniae as a producer of extended spectrum beta-lactamase (ESBL) has played an important role as a cause of infection in the neonatal high risk unit (NHRU) of the Autonomous Hospital Institute of the Universidad de Los Andes (AHIULA). In this paper an outbreak caused by this bacterial specie that affected neonates hospitalized in this unit during February 2007 is described. Besides, the environment and the personnel were studied as possible sources of this organism. The strains of K. pneumonia isolated from the outbreak had the same resistance phenotype, produced ESBL type TEM and SHV and belonged to the same genotype as the isolated strains from the hands and the soapy solutions, possible sources of infection. This indicates that it was the same clone. The outbreak was resolved using two important measurements: reinforcing hand washing and with the opportune treatment of neonates with imipenem.