Background: Spontaneous resolution of acute subdural hematomas (SDHs), occurring as the result of a traumatic injury, is well reported in the literature and rapidly resolving SDHs have been reported as well. Although the mechanism behind the rapid resolution of a SDH has not been well understood, there are postulated mechanisms for this phenomenon. The aim of this report is to present a patient who experienced the rapid resolution of a traumatic SDH, which was replaced by a subdural hygroma. Case Description: This 25-year-old man presented to the hospital with an acute left-sided SDH after a head-on motor vehicle collision. At the time of presentation, the patient had an acute SDH with 11 mm of midline shift. The hematoma resolved spontaneously within 48 hours and was replaced by a thin subdural hygroma. Conclusions: Rapidly resolving SDHs represent a phenomenon that has been well described, although is not entirely understood. The imaging findings of this patient suggest that cerebrospinal fluid washout is a mechanism that promotes acute SDH resolution. © 2018 Elsevier Inc.