Sandhoff's disease is a severe form of gangliosidosis GM2 which presents in the first year of life, basically as progressive psychomotor retardation and/or a macular red cherry spot. Our patient presented the clinical picture characteristic of the disease. Diagnosis was confirmed by determining the activity of hexosaminidases A and B in serum and of beta-N-acetil hexosaminases in fibroblast culture. In view of the fatal prognosis of the disease, in 1991 a transplant of alogenic bone marrow (TMO) was carried out to try to replace the enzymes. This required exhaustive radiological follow-up to determine the possible neuro-radiological changes seen in this storage disease. Although treatment was not successful, the neuro-radiological findings may be of interest as perhaps being characteristic of the GM2 gangliosidosis: 1. Bilateral thalamic hyperecogenity in the cerebral ecography. 2. Differences between the thalamo-putamen densities due to bilateral homogeneous thalamic hyperdensity on the CT scan. 3. Thalamic hypointensity both on T2 sequences and in proton density on MR with the cerebral white matter being progressively affected. In conclusion, we suggest that bilateral symmetrical thalamic changes are an early finding which is probably specific to the GM2 gangliosidoses and may be useful from the point of view of carrying out more specific investigations in infants suspected of having a degenerative neurological disorder.