Study to determine serotype, virulence and antibiotic resistance of 3 bacteria causing pneumonia in pigs in Tuyen Quang. Results showed that isolated A. pleuropneumoniae strains were serotype 2 (62.07%) and serotype 5 (20.69%). The strains of P. multocida isolated from serotype A (73.91%) and serotype D (26.09%). The strains of S. suis isolated from serotype 2 strain (32.69%), serotype 7 (25%) and serotype 9 (25%). The strains of 3 isolated bacteria have high virulence, causing substance 94.82 - 97.11% of experimental rats after intensive treatment of 12 - 48 hours. The strains of 3 isolates were highly susceptible to 3 ceftiofur, ampicillin and amikacin antibiotics.