Biochemical patterns of twenty five P. multocida strains isolated from poultry in Iran were determined by using hexoses, pentoses, disaccarides and polyhdric alcohols. All strains were able ferment sorbitol. manitol, galactose, dextrose, w fructose, glucose, Mannose, and sucrose. However each of them couldn't produce acid from dulcitol, inositol, arabinose, salicine, rhafinose and inoline. According to this pattern all of isolates belonged to subspecies (biotype) multocida. Antimicrobial sensitivity patterns were determined against1 3 different therapeutic agents. Among antibiotics tested chloramphenicol, combination of , sulfamethozine an trimethoprim and nitrofurantoion were found to be the most effective (100% sensitivity) followed by w tetracycline (96%), penicilline (88%), and gentamycine (79%). Serotyping by Hedleston f method showed that the isolates belonged to serotypes 1, 3, 4 and 3x4. Except serotype 1, others are reported for the first time from Iran in this research.