Abstract: Objective To investigate the relationship between isocitrate dehydrogenase 1 (IDH1) mutation and clinicopathological features in human supratentorial WHO gradeⅡ gliomas. Methods Ninety five supratentorial WHO gradeⅡ glioma patients were treated in our department from January 2009 to January 2011. The clinical data and tumor samples of each patient were collected. IDH1 mutation in the tumor was measured by sequencing the IDH1 gene of tumor specimen. The relationship between IDH1 mutation and the clinicopathological features was analyzed. Results There were 69 cases (72.6%) with IDH1 mutations were found, all of which were R132H type mutations. The mutation rates of diffuse astrocytoma, oligodendroglioma and oligoastrocytoma were 73.6%, 68.8% and 73.1% respectively. The mean ages of IDH1 mutant group and wild type group were significantly different(39.6±7.4) yr. vs. (46.9±11.6) yr., P<0.05. The mutant rates of patients aged ≥ 50 years and <50 years were 43.8% and 78.5% respectively (P<0.05), while those of male patients and female patients were 68.6% and 77.3% respectively (P>0.05). The mutant rates of patients whose tumor ≥ 5 cm and <5 cm were 60.0% and 90.0% respectively (P<0.05), while those of monolobe involvement group and deepen structures involvement group were 93.3% and 32.0% respectively (P<0.05). Conclusion The mutation of IDH1 in supratentorial WHO gradeⅡglioma is common, and is associated with patients' age, tumor size and tumor location.