Objective To investigate the expression level of fatty acid synthase (FASN) in different grades ofgliomas and its relationship with glioma malignancy.Methods Glioma U87 and U373 cell lines were routinely cultured in vitro;immunofluorescence assay was performed to detect the cellular localization of FASN in glioma U87 and U373 cell lines.Sixty-seven human glioma samples,collected in our hospital from March 2012 to March 2013,were used in our study;grade Ⅰ was noted in three samples by WHO grading,grade Ⅱ in 29,graded Ⅲ in 22,and grade Ⅳ in 13;immunohistochemistry was performed to detect the expression levels of FASN,CD34 and Ki-67 and microvascular density (MVD) in these human glioma samples.Spearman's correlation was used to analyze the relationship between FASN expression and both Ki-67 expression and MVD in human gliomas.Results (1) FASN could express in the cytoplasm of glioma U87 and U373 cell lines.(2) immumohistochemical staining indicated that FASN mainly located in the cytoplasm,Ki-67 in the cell nucleus,and CD34 in the cytomembrane.FASN expression in samples of grade Ⅰ (3.3683±0.6549) was significantly lower than that in samples of grade Ⅱ (4.0512±0.4859,P＜0.05),and FASN expression in samples of grade Ⅲ (4.1881±0.5755) was significantly lower than that in samples of grade Ⅳ (4.6996±0.5164,P＜0.05);MVD in samples of grade Ⅱ was significantly smaller than that in samples of grade Ⅲ(P＜0.05),and MVD in samples of grade Ⅲ was significantly lower than that in samples of grade Ⅳ(P＜0.05);Ki-67 expression in samples of grade Ⅱ was significantly lower than that in samples of grade Ⅲ (P＜0.05).(3) There was a positive and significant correlation between FASN expression and MVD (r=0.606,P=0.030);a positive and significant correlation between FASN expression and Ki-67 was also noted (r=0.636,P=0.014).Conclusion High expression level of FASN indicates high proliferation capability and high blood supply in haman gliomas.