Objective(s)The fractions of Candida albicans have been used as an immunomodulator. The present work assessed theeffect of different fractions of C. albicans on nitric oxide (NO) production by mice peritoneal macrophages.Materials and MethodsCell wall and cytoplasmic fractions of C. albicans ATCC 10321 strain were extracted. Mice peritonealmacrophages were purified and cultured. Different concentrations of both fractions and also killedC. albicans cells were used for macrophages stimulation and evaluation of NO production. NO amount wasdetected in culture supernatants of macrophages by Griess reagent. Also, MTT assay was performed toassess the viability of macrophages.ResultsThe results elucidated that suppressive effect of cell wall proteins on NO release was significant at the doseof 100 μg/ml (P=0.01), while cytoplasmic fraction increased NO amount at the dose of 1 μg/ml compared tothe control group (P=0.003). Augmentation of NO production was statistically significant at 200 killedC. albicans per well (P=0.006).ConclusionAccording to our findings, cytoplasmic fractions and killed C. albicans have a positive effect on NOproduction by peritoneal macrophages, while cell wall fractions did not. Therefore, it is proposed thatC. albicans fractions can be studied more as inflammation modulators.Keywords: Candida albicans, Macrophages, Nitric Oxid