We report three cases of L-2-hydroxyglutaric acidemia and three cases of Canavan disease. The L-2-hydroxyglutaric acidemia cases are the first biochemically proven Turkish cases. Magnetic resonance imaging findings in the cases and similarities between the two diseases are emphasized. Both diseases are characterized by predominant subcortical white-matter involvement and dentate nuclei lesions with variable basal ganglia involvement. Canavan disease differs from L-2-hydroxyglutaric acidemia by the presence of typical brainstem involvement.