$eta$-l, 3-glucans are well known to enhance the immune reactions, resulting in antitumor, antibacterial, antiviral, anticoagulatory and wound healing activities. $eta$-1, 3-glucans have various activities depending on molecular weight, degree of branching, conformation, water-solubility and intermolecular association. However, the $eta$-1, 3-glucans linked backbone structure is essential and $eta$-D-glucopyranosyl units are required for immunopotentiating activities. In this study, we tested the immunophamacological activities of insoluble $eta$-1, 3-glucan from Agrobacterium sp. R259 KCTC 10197BP and confirmed the following activities: (1) IFN-${gamma}$ production in PBMCs in the presence or in the absence of PHA, LPS, IL-18, and IL-12; (2) the induction of various cytokines in the spleen and thymus; (3) the adjuvant effect on the antibody production; (4) the cytotoxic and antitumor effects on cell lines and ICR mice. These results strongly suggest that $eta$-1, 3-glucan from Agrobacterium sp. R259 KCTC 10197BP possesses various immunopharmacologica1 activities.