Background: There is currently little data on the incidence, clinical outcome and management of traumatic interhemispheric subdural hematomas (IHSDHs). Methods: All patients admitted with an acute subdural hematoma (SDH) over a 5-year period at a Level I trauma center were included. A detailed review of all cases of large IHSDH (≥7 mm) was performed to document clinical presentation, management and outcomes. Results: Of 1182 patients with acute subdural hematomas (SDHs), 420 had IHSDHs (24%), and 50 were large IHSDHs. For patients with large IHSDH, the average age was 76 years (±11) and 44% were female. The average GCS was 12 on presentation (±4), and the average GOSE was 4 (±2). 66% of patients had associated cranial/ intracranial injuries (fracture, subarachnoid/epidural/SDH) and 26% required operations for acute convexity SDH. Three patients required operations for their IHSDH by inter hemispheric approach. By 10 weeks, 82% had a complete resolution of the IHSDHs. Conclusions: IHSDHs are often referred to as rare entities. Our results show they are common. Conservative management is often appropriate to manage even large IHSDHs, as most resolve spontaneously. This study will help document the occurrence of falx syndrome, as well as the management and outcomes of larger IHSDHs.