We report on a young patient who suffered from diabetes mellitus and neurosensorial deafness from the age of two. One year later she was noted to have deteriorated vision and the diagnosis of optic atrophy was made, her visual acuity decreased progressively. At the age of six she was admitted to our hospital because of thiamine responsive megaloblastic anemia, a rare clinical feature of Wolfram's syndrome (only 13 cases have been reported to date). Thiamine (75 mg/day) was commenced at a single oral dose with a rapid increase of Hb level after a few days of therapy. The insulin requirement didn't decrease during thiamine therapy, the C-peptide level after glucagon remained almost indosable. No improvement was observed in the deafness and in the optic atrophy. These findings suggest that diabetes mellitus and optic atrophy, in Wolfram's syndrome are not related to thiamine metabolism.