Vitamin A was used as adjuvant, comparatively with Al(OH)(3), in pertussis, tetanus and diphtheria vaccines. Both groups induced a primary immune response in mice, and one single booster dose elevated the antibodies titers in average 554 times to vitamin A groups and 104 times to Al(OH)(3). These antibodies titers correlate with sera IL-4 in immunized animals, suggesting a Th2 response. Other cytokines detected in the sera and/or lymphocytes culture supernatants (IL-2 and IFN-square) indicated that vitamin A could also modulate a Th1 response in DPT and acellular pertussis vaccines.