In the present study of the microbiological flora of 284 ulcera crurum we found 452 various bacterial strains. 174 (61.3%) of the 284 ulcera crurum were found in women, 110 (38.7%) in men with a predominance in the age group between 70-79 years. Staphylococcus aureus were the most frequent bacteria, with an isolation rate of 22,4%. Furthermore, gram-negative bacteria like pseudomonas (14.6%), proteus (10.2%) were isolated. Besides these other species of the group of enterobacteriaceae must be taken into consideration--especially Enterobacter and Klebsiella. In comparison to the results of bacterial isolation rates reported in the literature of the last 15 years, it is obvious that staph. aureus is most common in the bacterial invasion of ulcera crurum . An increase of isolation rates of pseudomonas and proteus and other gram-negative germs could not be found during the last 10 years. The variety of bacterial species on leg ulcers and the frequent occurrence of mixed flora give evidence of the importance of microbiological diagnostic and antibacterial therapy.