Objective To investigate the protein expression of phosphatidylinositol 3-kinase (PI3K), phosphorylated Akt B (p-Akt) and p-mTOR in human gliomas, and evaluate their clinical significance in clinicopathological status and prognosis of these patients with gliomas. Methods Eighty-eight patients, admitted to our hospital from September 2004 to September 2008, were chosen in our study; these patients were performed surgical resection and the samples were pathologically confirmed as gliomas. Another 20 samples, cut from the normal brain tissue were adopted as controls.Immunohistochemistry was employed to examine the protein expression of PI3K, p-AKT and p-mTOR.Then, the correlation of their expression with the clinicopathological features of the gliomas and prognosis of the patients was further analyzed. Results The positive expression rates of PI3K in gliomas and normal brain tissues were 68.18% (60/88) and 18.18% (16/88), respectively; those of p-AKT were 73.86% (65/88) and 17.05% (15/88), respectively;, those of p-mTOR were 75.00% (66/88) and 18.18% (16/88), respectively; the expression levels of these 3 proteins were all significantly higher than those in normal brain tissues (PI3K: x2=14.028, P=0.009; p-AKT: x2=15.132, P=0.008 and mTOR:x2=15.293, P=0.008). The positive expression rates of PI3K, p-AKT and p-mTOR were significantly different in the gliomas with pathological grades, different scores of Karnofsky performance status and different clinical stages (P＜0.05). In addition, the 5-year overall survival rate in PI3K-positive group,p-AKT-positive group and p-mTOR-positive group was significantly lower than in those negative groups (PI3K: x2=8.381, P=0.026; p-AKT: x2=12.923, P=0.011; mTOR: x2=13.252, P=0.013). Conclusion PI3K/Akt/mTOR signal transduction pathway is over-activated in gliornas, which is closely correlated to the grade-malignancy; and the positive expression of PI3K, p-AKT and p-mTOR may predict the poor prognosis of the patients with gliomas.