In this study, we investigate anti-allergic and anti-inflammatory effects of Leonurus sibiricus seed (LSS) extract in basophilic leukemia RBL-2H3 cells. To identify anti-allergic actions of LSS, the degranulation was evaluated in IgE and DNP-BSA stimulated RBL-2H3 cells. At the concentration of $100{mu}g/ml$ of methanol (MeOH) extract and Methylene chloride (MC) and Ethyl acetate (EtOAc) fractions, the degranulation was significantly inhibited 16.7%, 16.7% and 27.9% respectively. And then, to assess anti-inflammatory effects of LSS, IL-4 and IL-13 mRNA level were detected in PMA/ionomycin (PI)-induced RBL-2H3 cells and cell proliferation and IL-4 mRNA level in isolated splenocytes from Balb/c mice. LSS MeOH extract and MC and EtOAc fractions significantly decreased the level of IL-4 and IL-13 mRNA in PI-induced RBL-2H3 cells and showed inhibitory effects on cell proliferation and expression of IL-4 mRNA level in mouse splenocytes. Taken together, these results suggest that LSS has potential anti-allergic and anti-inflammatory effects and EtOAc fraction is the most effective in regulating immune responses.