Using monoclonal antibodies (Mabs) against Pasteurella multocida serotype B, a competitive ELISA was standardized and adopted to detect anti-hemorrhagic septicemia (anti-Hs) in cattle serum samples. Out of 72 serum samples, 64 were found negative for HS and only 8 exhibited slight positive reactions. Twenty four positive samples and 24 serum samples from apparently healthy cattle were run as controls. The test was very sensitive in detecting even low anti-HS titers due to the nature of monoclonal antibodies ‘ extreme specificity to HS. But the use of modified immunodot (IMD) assay in the detection of the presence of P. Multocida serotype B in nasal swab samples of 96 cattle collected from Batangas showed more sensitive results by IMD assay than by the indirect ELISA by 13.3 percent. Furthermore, crude capsular antigen- (CCA) based Mab was found to be more effective than whole cell-(WC) based Mab as antibody in IMD assay using nasal swab samples. Statistical analysis supported CCA Mab as more specific when used as diagnostic reagent in the determination of HS. Moreover, when the CCA-based Mabs were used by the IMD method in 303 unknown samples from cattle and carabaos (water buffaloes) from 14 provinces in the Philippines, 44 (14.5 percent) samples were found positive compared to known positive samples