Objective To investigate the effects of crude extract of Capparis spinosa L. fruit alka-loids (CSFA) on the maturation of murine bone marrow-derived dendritic cells (DCs). Methods CSFA was prepared and the contents were determined by high performance liquid chromatography. DCs were trea-ted with different doses (1, 2, 3 mg/ml) of CSFA. The viability of DCs, the expression of surface mole-cules and the ability of phagocytosis were detected by flow cytometry. The secretion of cytokines was meas-ured by ELISA. Western blot assay was performed to analyze the activation of key molecules in mitogen-acti-vated protein kinases ( MAPK) and nuclear factor-kappa B ( NF-κB) signaling pathways. Results The re-sults showed that CSFA alone had no significant influence on the expression of surface molecules and cyto-kines in DCs. However, it significantly decreased the expression of CD40, CD80, CD86 and MHC Ⅱ as well as the secretion of IL-12p40 and TNF-αthat were induced by lipopolysaccharides (LPS), but increased IL-10 secretion and the ability of phagocytosis after treating DCs with both CSFA and LPS. Further, the phosphorylation of p38, extracellular signal-regulated kinase (ERK) and c-Jun NH2-terminal kinase (JNK) and the nuclear translocation of NF-κBp65 induced by LPS were inhibited by CSFA. Conclusion CSFA could inhibit the maturation of DCs and the secretion of pro-inflammatory cytokines induced by LPS while in-creasing the secretion of the anti-inflammatory cytokine IL-10 and the ability of phagocytosis, which might in-volve MAPK and NF-κB signaling pathways. This study suggests that CSFA could be used as a potential im-munosuppressant.