Abstract：Objective: To determine the levels of miR-497 in cancer tissues and serum of patients with astrocytoma, analyze the change of serum miR-497 before and after surgical treatment and evaluate the potential of miR-497 as a biomarker of astrocytoma. Methods：The cancer tissues from 8 astrocytoma patients, the adjacent non-tumor tissues from 4 astrocytoma patients, the normal tissues from 3 controls, the serum samples from 133 untreated astrocytoma patients (WHO Ⅱ grade 55 cases, grade Ⅲ 33 cases, grade Ⅳ 45 cases) and 80 age and sex-matched healthy individuals were collected to determine the level of miR-497 by quantitative reverse-transcription PCR (qRT-PCR). miR-497 levels in the paired serum samples before and after operation from 14 astrocytoma patients were determined to observe the effect of surgical treatment on miRNA. The diagnostic value of miR-497 for astrocytoma was assessed by ROC curve. Results：miR-497 expression was significantly lower in cancer tissues than that in adjacent non-tumor tissues (F=13.78, P<0.05). Serum miR-497 levels in astrocytoma patients was also significantly lower than that in healthy controls ［(112.69±54.58) fmol/L vs (254.32±142.12) fmol/L, t=10.31, P<0.01. The area under ROC curve (AUC^ROC) of miR 497 was 0.894 (95% CI, 0.853~0.935). The sensitivity was 82% and the specificity was 90%. The serum levels of miR-497 were significantly increased after operation ［postoperative (165.69±56.87) fmol/L vs preoperative (93.77±38.50) fmol/L, t=3.92, P<0.01. Conclusion：The expression of miR-497 decreased in cancer tissues and serum from astrocytomas patients, so it may be used as noninvasive biomarker for diagnosis and prognosis of astrocytoma.