One of the pseudorabies virus glycoproteins, gII, was integrated into Quil A matrix and formed an antigenic presentation structure known as immunostimulating complexes (ISCOMs). The gII ISCOMs protected mice from a lethal infection of pseudorabies virus (PrV). Subsequently, the efficacy of gII ISCOMs as a vaccine was evaluated in pigs, a natural host species of PrV. Immunization of pigs with gII ISCOMs protected them from PrV-induced acute symptoms and death. The serum obtained from immunized pigs was clearly discriminated from that of infected pigs by immunoprecipitation. The data indicated that the ISCOM technique was useful in PrV subunit vaccine preparation and demonstrated the importance of glycoprotein gII as a component of PrV vaccine.