To investigate the effect of Korean mistletoe on stimulation of macrophage, the activity to induce interleukine-1(IL-1) and tumor necrosis factors-${alpha}(TNF-{alpha})$ from murine peritoneal macrophage by its extracts originated from oak was examined. From in vitro analysis of the cytokines using the culture supernatants of macrophages stimulated with its extracts for 1hr, it was found that Korean mistletoe induces IL-1 and $TNF-{alpha}$ from murine macrophage. Furthermore, both extracts of Korean mistletoes that were extracted with distilled water and 2% acetic acid exhibited a significant activity to induce two cytokines. In the stimulation for 30 min, Korean mistletoe at concentration of $1{sim}100;mu/ml$ showed a significant induction of IL-1 from macrophage until 24 hrs after stimulation, showing maximal activity on $5{sim}10;hrs;at;10{sim}100;mu/ml$. On the other hand, $TNF-{alpha}$ was induced on the early period, 2 hrs, after stimulation at a wide range of concentration, $1{sim}500;mu/ml$. In addition, the fraction of Korean mistletoe from 80% saturated ammonium sulphate precipitation showed a significant activity to induce both cytokines from macrophage. The present study demonstrates that Korean mistletoe contains immunoregulatory factors responsible for stimulating murine macrophage to secrete IL-1 and $TNF-{alpha}$ which play an important role in immune responses, and suggests that the activity of Korean mistletoe to induce two cytokines is functioned by a possible independent stimulation manner.