The aim of the present study was to determine the source of nosocomial outbreak due to Burkholderia cepacia by molecular techniques. A total of 11 B. cepacia strains were isolated; nine from blood and one from sputum of patients without cystic fibrosis, and one from reverse osmosis water at a local hospital in Guangzhou, China. Analyses of 11 strains by the Sau-PCR assay and pulsed-field gel electrophoresis revealed that nine strains obtained from the blood of outpatients in a hemodialysis unit and one strain from reverse osmosis water had identical DNA profiles, indicating that the reverse osmosis water supply could be a source of infection.