Spontaneous intracranial hypotension is an infrequent clinical entity characterized by orthostatic headache, low cerebrospinal fluid pressure, and magnetic resonance imaging findings of diffuse pachymeningeal gadolinium enhancement without previous history of head trauma or lumbar puncture. A 24 year-old healthy woman was referred after having daily headaches for two weeks. She described a headache that occurred soon after assuming an upright position and disappeared after resuming a recumbent position. The cerebrospinal fluid showed pleocytosis primarily lymphocitic, raised protein content and an opening pressure of 20 mm H2O. Magnetic resonance imaging of the head showed diffuse pachymeningeal gadolinium enhancement. Radioisotope cisternography using 99mTc-DTPA confirmed the cerebrospinal fluid leak in the thoracic region. With conservative treatment the patient improved in a few days and the headache disappeared. Radiological findings, together with a compatible clinical condition, help to establish the diagnosis of spontaneous intracranial hypotension and avoid the use of unnecessary clinical investigations.