This paper presents a study on 155 isolates of Pasteurella multocida isolated from different outbreaks of haemorrhagic septicaemia (HS) throughout Malaysia. This organism was also isolated from the lymph nodes of the upper respiratory tract of nine out of 800 healthy cattle and buffaloes examined in the State of Perak. They were subjected to cultural and biochemical examinations. All 164 strains produced indole, oxidase and catalase. None of the strains fermented rhamnose, raffinose, starch, inulin, adonitol, dulcitol, inositol, salicin or aesculin. Of the fermentable sugars the positive reactions ranged from 0·6 to 91%. They were all serotyped by the passive mouse protection test (MPT) and 117 of them were subjected to the haemagglutination (HA) test. Of the 117 strains which were subjected to both the MPT and HA test, 92 belonged to Carter’s type B, three belonged to Carter’s type D and 22 could not be classified as types A, B, D or E (untypeable) by the MPT, whereas by the HA test 77 belonged to Carter’s type B, four belonged to Carter’s type D and 36 were untypeable. No distinct group pattern was observed between the biochemical reactions and the serological types.