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Objective/Background: Glioblastoma (GB) is the most common primary malignant brain tumor in adults. Ki-67 is a nonhistone nuclear protein that is expressed by cells entering the mitotic cycle and is associated with the transcription of ribosomal RNA (rRNA). In gliomas, the extent of expression of Ki-67 is roughly proportional to the histologic grade. Over the years, association studies were conducted trying to link the poor outcome in different types of malignant tumors to the Ki-67 proliferative index. This study is designed to investigate the relationship between the proliferation marker, Ki-67, and the overall survival amongst glioblastoma patients diagnosed between 2006 and 2012 at a single institution in Riyadh, Saudi Arabia. Methods: This is a retrospective cohort study which investigated the status of Ki-67 labeling index in glioblastoma patients diagnosed at King Abdulaziz Medical City, Riyadh, Saudi Arabia, between 2006 and 2012. The Kaplan–Meier survival analysis was used to assess the overall survival (OS) and the Mantel–Cox log-rank test was used to compare the survival curves. Multivariate analysis using Cox proportional-hazards model was used to investigate other factors that might influence the overall survival. Results: A total of 44 glioblastoma patients were included in the study. The median age at diagnosis was 56 (1–91) years. The 12-month survival rate for all glioblastoma patients was 48%. The median survival for patients with Ki-67 labeling index of ≤27%, and >27% was 11 months and 14 months, respectively. Conclusion: The difference between the survival curves of patients with Ki-67 labeling index of ≤27%, and Ki-67 of >27% was statistically insignificant (p = .130). Therefore, Ki-67 labeling index alone cannot predict survival in glioblastoma patients.