In model animal experiment A, ICR mice were immunized with ovalbumin (OVA) adjuvanted with Quil A or mineral oil or their combination (Quil A+oil). In model animal experiment B, ICR mice were immunized with foot-and-mouth disease virus (FMDV) antigens or with a commercially available oil adjuvanted foot-and-mouth disease (FMD) vaccine (type O) alone or mixed with Quil A. After that, serum samples were collected to analyze specific IgG and IgG subclasses IgG1, IgG2a, IgG2b, and IgG3. In experiment C, pigs were immunized with FMD (type O) vaccine alone or together with Quil A. Serum samples were collected before and 4 weeks after immunization to analyze indirect haemagglutination (IHA) titers. Results from experiment A indicated a synergistic effect of Quil A and oil on IgG and the subclass responses. Experiment B revealed that supplement of Quil A in FMD vaccine significantly increased IgG and the subclass responses in mice. Experiment C demonstrated that supplement of Quil A in the FMD vaccine significantly enhanced humeral immune responses (as determined by IHA test) in pigs. It is concluded that supplement of Quil A in FMD vaccine can significantly enhanced immune responses and could be an alternative way to improve FMD vaccination in pigs.