Traditional immunological assays used to serotype Actinobacillus pleuropneumoniae have been problematic due to cross- reactivity between serotypes, particularly serotypes 6 and 8. To avoid these serological cross-reactions, a multiplex PCR assay was developed to detect A. pleuropneumoniae and identify serotypes 1, 2, and 8. Primers specific to the conserved capsular polysaccharide export region of A. pleuropneumoniae serotype 5 amplified a 880 bp fragment in all serotypes excluding serotype 4 or a 489 bp DNA fragment in all serotypes including serotype 4. Primers specific to the capsular polysaccharide biosynthesis regions of A. pleuropneumoniae serotypes 1, 2, and 8 amplified a 1.6 kb, a 1.7 kb, and 970 bp fragment in the respective serotype. This PCR assay detects A. pleuropneumoniae and identifies serotypes 1, 2, and 8.