Abstract: Objective: To investigate the trend of alteration of pathogens in infected burn wound before healing. Methods: The data were collected and analyzed from the data bank of pathogens collected in a burn unit. Only the bacteria from patients who were found to have over 3 positive cultures and the drug resistance of the bacteria determined were included in this retrospective study. The interval between the first isolation and last one was usually larger than one week. The species ratios of common bacteria were calculated after 1, 2, 3, 4, 5 and over 6 weeks from the first isolation.Results: The isolateion rates of S. aureus, Proteus sp. and Klebsiella pneumoniae were increased with the prolonged existence of open wounds, and species ratio of S. aureus was the highest among all species of bacteria at all time points, reaching 50% in 6th week, but the species ratios of Enterococcus sp., Enterobacter cloacae and Acinetobacter sp. declined. Compared with that of the period of 1995-1997 and 1998-2000, the species ratios of S. aureus, Proteus sp. and Acinetobacter sp. were increased significantly during the period of 2001-2003, and species ratios of Pseudomonas aeruginosa and E. coli were decreased during the same period. Conclusion: The results suggested that S. aureus was the prominent pathogen of infected burn wounds in our burn unit, and its infection might take place any time after injury. It was very likely that the majority infection by Enterococcus sp, and Acinetobacter sp.accurred at the early stage of burn injury, and infection by Proteus sp. and Klebsiella pneumoniae in burn wounds occurred several weeks later.