Abstract
A relationship between proteinase activity of culture filtrates of Pseudomonas aeruginosa strains and their virulence on mice was shown. High virulence strains displayed a much higher enzyme activity than low virulence strains. These results are supported by statistical analysis. The determinating of proteinase activity on the 4th day of culture may be used as a criterion for virulence of Pseudomonas aeruginosa strains.