Fabry's disease is an X linked inborn error of metabolism due to deficient activity of the lysosomal enzyme alpha galactosidase A. Previously unrecognised Fabry's disease presenting in a 52 year old man being investigated for progressive dysarthria and ataxia is discussed. Brain magnetic resonance imaging suggested the presence of small vessel disease but skin biopsy (done to exclude cerebral autosomal dominant arteriopathy with subcortical infarcts and leucencephalopathy) showed typical changes of Fabry's disease. This diagnosis was confirmed by subsequent enzyme assays. The authors contend that Fabry's disease should be excluded, at least on clinical grounds, in patients with otherwise unexplained cerebrovascular disease.