Recently, research efforts in identifying prognostic molecular biomarkers for malignant glioma have intensified. Cysteine-rich protein 61 (CCN1) is one of the CCN family of matricellular proteins that promotes cell growth and angiogenesis in cancers through its interaction with several integrins. In this study, we investigated the relationships among CCN1, O-6-methylguanine-DNA methyltransferase expression, the tumor removal rate, and prognosis in 46 glioblastoma patients treated at the Okayama University Hospital. CCN1 expression was high in 31 (67 %) of these patients. The median progression-free survival (PFS) and overall survival (OS) times of patients with high CCN1 expression was significantly shorter than those of patients with low CCN1 expression (p < 0.005). In a multivariate Cox analysis, CCN1 proved to be an independent prognostic factor for patient survival [PFS, hazard ratio (HR) = 3.53 (1.55-8.01), p = 0.003 and OS, HR = 3.05 (1.35-6.87), p = 0.007]. Moreover, in the 31 patients who underwent gross total resection, the PFS and OS times of those with high CCN1 expression were significantly shorter than those with low CCN1 expression. It was concluded that CCN1 might emerge as a significant prognostic factor regarding the prognosis of glioblastoma patients.