A previously healthy 34-year-old woman and a previously healthy 35-year-old woman with spontaneous intracranial hypotension (SIH) presented within 1 week of the onset of symptoms. Brain magnetic resonance (MR) imaging with gadolinium demonstrated no abnormality, whereas spinal MR imaging revealed extradural fluid collection in both patients. Both patients were treated conservatively with bed rest and intravenous hydration. Their symptoms almost completely resolved. We suggest that spinal MR imaging findings of extradural fluid collection can help to establish the early diagnosis of SIH.