We have been focussing on discovery of natural compounds that have immunoregulatory activities for many years. In the present study, we investigated if chlorogenic acid (CRA), a polyphenolic compound, has an immunoadjuvant activity. Prior to examining the immunoadjuvant activity, effect of CRA on proliferation of T- or B-lymphocyte was determined. Results showed that CRA enhanced the proliferation of those lymphocytes in dose-dependant manner (P<0.05), and the proliferation enhancement by CRA was appeared to be more effective to B-cells than to T-cells. Based on these observations, it was tested with bovine serum albumin (BSA) and Candida albicans cell wall (CACW) as antigenic sources if CRA has an immunoadjuvant activity. In experiments, BSA alone or a mixture of BSA plus CRA was injected intraperitoneally to mice (BALB/c strain). For a negative control, mice were given only diluent (DPBS) by the same route. In other experiment, CACW was tested by the same way as did with BSA. Three weeks after the first immunization these animals were boosted. Antisera collected from the mice one week after the booster were analyzed by ELISA. Results displayed that the induction of anti-BSA antibody was increased in mice that received the mixture of BSA and CRA as compared to anti-BSA induction in BSA only-given mice groups (P<0.05). In case of CACW, a similar observation as did with BSA was made, resulting in that there was app. 40% increased production of the anti-CACW antiserum from the combination (CACW plus CRA)-received mice as compared to antiserum induction from CACW alone-given animals. Taken all together, these data indicate that CRA has an ability of enhancing antibody production regardless of nature of antigenic sources. Presumably, activation of B-cell proliferation by CRA may plays an important role in the immunoadjuvant activity of the polyphenolic compound.