SummaryAlthough MRI detects the while lesions of multiple sclerosis within the brain with high sensitivity a minority of patients have normal brain MRL. We describe 20 patients, selected from over 170 who had undergone brain imaging with minimal (n = 12) or no (n = 8) abnormalities (median numbern of lesions = 1, range, (0–3) but in whom spinal MRL was abnormal. Twelve had clinically definite or laboratory supported definite multiple sclerosis according to the Poser Crietria: one had clinically probable diease and seven, not fulfilling the Poser criteria, were classified as possible multiple sclerosis. All had presented with symptoms and signs referable to the spinal cord or optic nerves. Eleven had a primary progressive course, eight relapsing-remitting and only one secondary progressive. Moderrure or severe disability was the rule in the primary progressive cases: all the relapsing-remitting patients had minimal disability. All had at least one lesion visible in the spinal cord (median 2; range 1–6). In patients in whom the diagnosis of multiple sclerosis is not supported by abnormalities on brain MRL, imaging of the spinal cord can beof considerable value.