Venous leg ulcers are an important cause of morbidity in a significant percentage of the world population. The percentage of leg ulceration, either active or healed, in the European population is about 1%-2%. The aim of this study was to analyze the rate of colonization and qualitative composition of the bacterial flora isolated from leg ulcers in patients admitted to Dermatology Department, Poznań University of Medical Sciences, during the 1998-2002 period, with special reference to the infection risk factors. Bacteriological diagnosis of 175 wound swabs was performed in compliance with compulsory laboratory methods. In 173 positive results, the predominant culture composition included Staphylococcus aureus (56.57%), Pseudomonas aeruginosa (37.14%), Enterococcus faecalis (22.29%), Proteus mirabilis (13.71%) and Escherichia coli (12.57%). There was a significant increase in the incidence of Pseudomonas aeruginosa, Enterococcus faecalis and Escherichia coli, along with a decrease in the incidence of Staphylococcus aureus isolation during the study period. The rate of yeast-like fungi strains, mainly Candida albicans, recorded in culture composition showed a systematic increase. Changes in the qualitative and quantitative composition of bacterial flora, presence of multiple isolates, and concomitant diseases that may influence the characteristics of leg ulcer disease were closely monitored.