Estimation of tumor recurrence in meningioma patients is one of the important clinical challenges. The prognostic impact of immune modulatorymolecule PD-L1 in several malignancies has been demonstrated. We studied the association of PD-L1 expression in meningioma with tumor recurrence and the underlying mechanism of its activation. Immunohistochemical staining(IHC) was performed for detection of PD-L1and NFKB2 on whole sections of meningiomas diagnosed between1998-2016 at TorontoWesternHospital. The biologic role of hypoxia in activation of PD-L1 in meningioma was investigated using gene set enrichment analysis(GSEA)-based on RNAseq data in validation cohorts. We analyzed a total of 93 meningioma cases: F/M ratio58/35;WHOgrade I(41),II(43),III(9),42(47%)cases with tumor recurrence and median follow up was 6.97yrs. PD-L1 expression on tumor cells(PD-L1TC) in 33(35%) cases was identified with distinctive patchy distribution. Univariate analysis indicated expression of PD-L1TC as a prognostic factor for tumor recurrence(p<0.0001). Multivariate analysis showed that PD-L1TC expression is an independent prognostic factor for tumor recurrence after adjusting for extent of resection(EOR),WHO grade and maximum tumor diameter(p<0.0001). Analysis of RNAseq data of two GEOmeningioma studies demonstrated prominent expression of NFKB activation associated with PD-L1expression. IHC analysis confirmed increased expression of NFKB2 protein in 26(30%)cases,which correlated with PD-L1TC expression(p=0.02). Furthermore,GSEAon a RNAseq data of 88 sporadic meningiomas using Hypoxia gene signature of HUVEC cells we found that the hypoxic sporadic meningiomas have significantly elevated PD-L1 expression(p<0.001). Our data strongly suggest that PD-L1TCexpression serves as a significant prognostic marker for tumor recurrence and. We found that hypoxia andNFKB2 activation are potential underlying mechanisms. These results also provide a rationale for potential adjuvant therapeutic role for PD-L1 inhibitors in meningioma.