The development of new immune potentiators for human vaccines is an important and expanding field of research. In the present study, the ability of the capsular polysaccharide from Neisseria meningitidis serogroup A (CPS-A), a mannose-containing carbohydrate, to enhance the antibody production against a co-administered model vaccine antigen, is examined. A protein-meningococcal serogroup C capsular polysaccharide (CPS-C) conjugate was selected as the model antigen for this study. After subcutaneous immunization of Balb/C mice, the conjugate mixed with CPS-A induced higher anti-CPS-C IgG and IgG(2a) antibody levels and higher anti-meningococcal serogroup C bactericidal titers than the conjugate alone or mixed with CPS-C. The immuno-stimulatory properties exhibited by CPS-A and the fact that vaccines based on purified CPS-A has been safely used during decades to fight the serogroup A meningococcal disease, support the proposal to use CPS-A as immune potentiator for human vaccination studies.