PURPOSE: Late juvenile neuronal ceroid lipofuscinosis (NCL) is a lysosomal neurodegenerative disorder caused by the accumulation of lipopigment in neurons. Our purpose was to characterize the MR imaging and spectroscopic findings in three children with late infantile NCL. METHODS: Three children with late infantile NCL and three age-matched control subjects were examined by MR imaging and by localized MR spectroscopy using echo times of 135 and 5, Normalized peak integral values were calculated for N-acetylaspartate (NAA), choline, creatine, myo-inositol, and glutamate/glutamine. RESULTS: MR imaging revealed volume loss of the CNS, most prominently in the cerebellum. The T2-weighted images showed a hypointense thalamus and hyperintense periventricular white matter. Proton MR spectra revealed progressive changes, with a reduction of NAA and an increase of myo-inositol and glutamate/glutamine, In long-standing late infantile NCL, myoinositol became the most prominent resonance. Lactate was not detectable. CONCLUSION: MR imaging in combination with proton MR spectroscopy can facilitate the diagnosis of late infantile NCL and help to differentiate NCL from other neurometabolic disorders, such as mitochondrial or peroxisomal encephalopathies.