DNA vaccines have been widely used as effective means of eradicating a variety of viruses, parasites, bacteria as well as means of alleviating allergic and autoimmune diseases and tumors. As interleukin 1 (IL-1) plays an essential role in augmenting both cellular and humoral immune responses to foreign antigens, it may represent a good candidate for an adjuvant to DNA vaccines. Since the inflammatory activity of IL-1 may have a restricted application to DNA vaccines, we explored the possibility of augmenting immune response without unwanted inflammatory effect using IL-1beta 163-171 peptide, which is essential for IL-1 receptor 1 binding. A DNA fragment encoding the human IL-1beta 163-171 peptide of concern was fused to the Hepatitis B virus (HBV) core DNA vaccine, and injected into mice to analyze its immune responses. Compared with the control mice which received hepatitis B virus core antigen (HBcAg) alone, significant increase in not only the HBcAg-specific antibody response but also in T cell proliferation was observed in mice which received IL-1beta 163-171-HBcAg. These results suggest that the DNA fragment encoding the IL-1beta polypeptide of aa 163-171 might represent a good candidate for an adjuvant of DNA vaccines.