The purpose of this study was to assess the antitumor and immunomodulatory effects of the aqueous extract from Daphne gnidium in mice -bearing melanoma tumor. Balb/C mice were subcutaneously implanted with B16-F10 cells and treated intraperitoneally with the aqueous extract at 200 mg /kg b.w for 21 days. After euthanization on day 22, the tumors were weighed; lymphocyte proliferation, cytotoxic T lymphocyte (CTL) and NK cell activities were evaluated using the MTT assay. Macrophage phagocytosis was studied by measuring the lysosomal activity. In addition to its potential to inhibit the growth of the transplantable tumor, the aqueous extract remarkably induces splenocyte proliferation and both NK and CTL activities in tumor-bearing mice. The aqueous extract was also seen to have promoted lysosomal activity of host macrophages.