Objective: To determine the prevalence of developmental venous anomaly in diffuse glioma adult patients. Methods: We performed a retrospective cohort study (2010-2016) of consecutive adult patients harboring a supratentorial diffuse glioma in two centers: Sainte-Anne Hospital (experimental and control sets), and Pitié-Salpêtrière Hospital (external validation set). We included 219 diffuse glioma patients (experimental set), 252 brain metastasis patients (control set), and 200 diffuse glioma patients (validation set). The inclusion criteria were: age ≥18 years at diagnosis, histopathological diagnosis of diffuse glioma according to the 2016 World Health Organization classification of tumors of the central nervous system, surgery as first-line treatment without previous oncological treatment, available pre-surgical MRI performed with similar acquisition protocol, and absence of a nodular-like or a ring-like pattern of contrast enhancement on MRI that may preclude the identification of a possible developmental venous anomaly within the glioma. Results: We found more developmental venous anomaly in the experimental set (21.5%) than in the control set (5.2%; p<0.001). Similarly, we found more developmental venous anomaly in the validation set (23.5%) than in the control set (5.2%; p<0.001). There was no difference of the developmental venous anomaly prevalence between experimental and validation sets. The developmental venous anomalies distribution was not significantly associated with histopathological, molecular or imaging findings of the diffuse gliomas. Conclusions: We report and replicate in an external cohort a high prevalence of developmental venous anomaly in diffuse glioma adult patients, which suggests a potential underlying common predisposition or a causal relationship that will require deeper investigations.