Propolis is the generic term for the resinous substance collected by honey bees from a variety of plant sources. In this study, we have assessed the immunomodulatory properties of propolis (P) and fermented-propolis (FP) in BALB/c mice. Mice were subjected to gavage once a day (for 14 days) with 50, 100, 200 mg/kg body weight P, FP, or vehicle. Lymphocytes were isolated from the spleen and mesenteric lymph nodes (MLN) and the immune cell proportions, proliferative activities, and cytokine production were evaluated. The P- and FP-administration induced similar, but differential, alterations in the percentage of immune cell populations and their biological functions, including cytokine production and NK cell cytotoxicity. The proportion of$ CD4^+$ and $CD8^+$ T cells in the spleen was increased slightly in the P- and FP-administered mice as compared to the vehicle-treated mice. In MLN, the percentage of $CD4^+$ T cells was increased significantly in the 200 mg/kg P-treated mice. The mice which were treated with P and FP evidenced significantly increased interferon-$gamma$ and interleukin-4 production in concanavalin A-stimulated splenocytes, whereas the production of theses cytokines was not shown to be induced by P-treatment. In addition, NK cell activity was also increased dramatically by the administration of P and FP. Collectively, these findings showed that P and FP are wide-spectrum immunomodulators, which may modulate both innate and adaptive immune responses.