We present a patient of 20 years of age with glutaric aciduria type 1 (GA1) and normal psychomotor development. Her symptoms consisted of a few convulsions between 2.5 and 4.5 years of age. She was diagnosed at 9 years of age because of the typical alterations of GA1 that appeared in computed tomography and magnetic resonance (MR) imaging studies. Enzymatic activity in fibroblasts culture was nonexistent and glutarate excretion was elevated in the annual controls where this was investigated from the diagnosis of the disease so far. MR studies showed hyposignal in T1 of the subcortical white matter, severe dilatation of the Sylvian region and temporal fossa subarachnoid spaces, and hypoplasia of the subjacent cerebral parenchyma and of both temporal lobes. The corpus callosum and the surrounding zones appeared very enlarged and with signal changes. Spectroscopic MR showed signs of membrane instability and cellular impoverishment in subcortical white matter and basal ganglia and presence of lactic acid. Macrocephaly always maintained centiles over 98. The patient has no abnormal movements or motor disturbances, her behavior and intelligence being normal and she is able to follow studies of middle level.