Spontaneous intracranial hypotension (SIH) is a rare disabling condition whose main clinical manifestation is orthostatic headache. We analysed clinical characteristics in relation to time to resolution in 90 consecutive patients diagnosed with SIH at our centre between 1993 and 2006. After excluding 7 patients lost to follow-up, the remaining 83 cases were divided into four groups: Group A (53 cases) with progressively worsening orthostatic headache; Group B (3 cases) with severe acute-onset orthostatic headache; Group C (9 cases) with fluctuating non-continuous headache, of mild severity, that, in 33% of cases, did not worsen on standing; Group D (18 cases), 5 with a previous history of headache, 14 with orthostatic headache, and 10 with altered neurological examination. Complete symptoms and neuroradiological resolution occurred during follow-up in Groups A, B and D, but was longer in Group D probably in relation to more severe clinical picture with altered neurological examination. However, after a mean of 52 months (range 24-108), none of the nine Group C patients had MRI indicating complete resolution. The main characteristic of Group C related to incomplete resolution was delayed diagnosis. These preliminary findings suggest that early diagnosis of SIH correlates with better outcome, further suggesting that patients with a new headache that may worsen on standing or sitting should undergo MRI with contrast to expedite a possible SIH diagnosis, even if the pain is relatively mild.