Chronic subdural hematoma (CSDH) is prevalent among elderly populations worldwide, and its mysterious pathogenesis has been discussed in the literature for decades. The issues remaining to be solved in regard to CSDH include the initiating events; the bleeding into the subdural space and the formation of the outer and inner membranes, its development; increase and liquefaction of hematoma, the optimal treatments, and the natural history. The pathophysiology is becoming more clear due to recent findings from computed tomography studies and human models of CSDH. In this work, we review previous studies on CSDH and present a new integrated concept about the development of this common condition after head injuries.