Amino asid metabolism was studied by thin layer chromatography in 25 Pasteurella multocida strains isolated from various manifestations of the disease chicken septicemia. Six amino acids were used: DL-ornithin, L-cystein, L-asparagin, DL-serin, L-arginin and Acidum glutaminicum. The Pasteurella strains studied include in their metabolism the amino acid asparagin, but serin and cystein are excluded. The strains isolated from birds suffering from acute and atypical septicemia do not metabolize ornithin, while these isolated from birds having wattles oedema or from calves suffering from arthritis metabolize it. The reaction of Pasteurellae to arginin and glutamic acid varies and no regularity in this respect is observed. Strains isolated from calves suffering from bronchopneumonia do not include in their metabolism any one of the named amino acids. As a result of the test applied a correlation between the Pasteurella multocida biotypes assessed by the authors and the amino acid metabolism was established. This is one proof more that the isolated pasteurellae can be groupped in two big biotypes by the tests for virulence in birds and including in their metabolism the amino acid ornithin.