The extract from ECMS was investigated for its effect on the humoral immune responses to foot-andmouth disease vaccination. Fifty-six micewere randomly divided into seven groupswith eight animals in each.Mice in groups 5 to 7were subcutaneously (s.c.) injected with 0.5 mg DEX daily for 4 days to induce immunosuppression. The animals were then orally given ECMS (200 μg in 250 μl saline) in groups 3 and 6 or 250 μl saline in group 2, or s.c. injected with ECMS (50 μg in 100 μl saline) in groups 4 and 7 or 100 μl saline in group 5. After that, the animals in groups 2 to 7 were s.c. immunized twice with 100 μl of commercial oil-adjuvanted bivalent FMDV vaccine (serotypes O and Asia 1) at intervals of 21 days. Mice in group 1 received injection of 100 μl saline only. After 2 weeks, blood was sampled to determine FMDV-specific IgG and isotype IgG1, IgG2a, IgG2b and IgG3. Results indicated that oral administration or s.c. injection of ECMS augmented responses of specific IgG and most IgG isotypes. Giving ECMS tended to enhance serum-specific IgG and IgG isotype responses of mice immunosuppressed by s.c. injection of DEX. Considering the safety and immunomodulatory effect of ECMS in both normal and immunosuppressed mice demonstrated in the present study, this extract deserves further investigation to evaluate its potential in improving FMD vaccination in farmanimals such as pigs, sheep and cattle. © 2009 The Societies and Blackwell Publishing Asia Pty Ltd.