We report an unusual case of spontaneous acute spinal subdural hematoma. To date, only a few cases of magnetic resonance imaging (MRI) demonstration of such a pathology have been reported in the medical literature. We analyse the pathogenesis, clinical presentation, magnetic resonance imaging results, intraoperative findings and prognosis of this rare condition. We would like to stress that prompt and non-invasive diagnosis by MRI sagittal sections leads to efficient surgical treatment.