OBJECTIVE: To investigate the anti-inflammatory effect of pretreatment with quercetin on macro- phages after Candida albicans infection. METHODS: RAW 264.7 macrophages were used as a target cell line. Cell viability after treatment with quercetin at different time points was detected by Carboxyfluorescein diacetate, succinimidyl ester. Phagocytic function of macrophages was deter- mined by a fluorometric assay. Cytokine tumor ne- crosis factor a (TNF-a) production was measured by enzyme-linked immunosorbent assay. F-actin cy- toskeleton of L929 cells was stained by Alexa Fluor 488-phalloidin. RESULTS: Pretreatment with quercetin decreasedcell viability only at the highest concentration of 37 μg/mL 2, 24, and 48 h after the treatment. The phagocytic efficiency of macrophages pretreated with quercetin was significantly decreased in a time- and dose-dependent manner. F-actin label- ing showed that the actin cytoskeleton of the cells started to break down 2 h after treatment. More- over, it notably inhibited cytokine TNF-a produc- tion after Candida albicans infection. CONCLUSION: Pretreatment with quercetin in- duced an anti-inflammatory effect against Candida albicans infection in macrophages.