Previous examinations of the CNS in children with the Zellweger cerebrohepatorenal syndrome using 1H-MRS demonstrated a decreased N-acetylaspartate/Choline (NAA/Cho) ratio and increased mobile lipids. Wehypothesized that a decreased NAA/Cho ratio was already present at birth. Patient: The patient was a hypotonic, term neonate. The anterior fontanelle was very large, whereas the head circumference was small(32 cm, <P3). Renal ultrasonography showed small cysts. Laboratory examination showed elevated ratios of C26/C22 and C24/C22 fatty acids. Pipecolic acid and bile acids in plasma were elevated. Methods: MRI and 1H-MRS were performed in a 1.5 T system on the 12th day of life. MR imaging included T1 (TR/TE 450/30 ms), T2 (TR/TE 3000/50,150 ms), and IR(TR/TI/TE 2500/800/30) weighted images. Following imaging, 1H-MRS was performed. MRS measurements included multi echo (TE: 30 ms, 136 ms and 272 ms) single volume (PRESS) experiments (TR: 2000 ms, VOI dimensions were 60 × 40 × 15 in AP × LR × FH direction). Spectra were processed using a gaussian multiplication of 5 Hz and exponential multiplication of -4 Hz (line-broadening). Peak analysis was performed by integrating single peaks of interest using the manufacturer's software. NAA/Cho ratios were calculated and compared to reference values for neonates obtained in our institute.Results: MR images showed abnormal, symmetrical gyration patterns of the cerebrum: pachygyria as well as polymicrogyria were demonstrated. The right part of the cerebellum was hypoplastic. Hypomyelination was demonstrated in the Rolandic gyrus. 1H-MRS demonstrated a NAA/Cho ratio of 0.66, the lower limit for normal term neonates being 0.85. At 1.33 ppm a lactate resonance was seen with a height of 40% of the NAA peak. Lactate is not present in normal term neonates. A smaller peak was identified at 1.11 ppm. This resonance could be attributed to either mobile lipids or, alternatively, to β-OH butyrate. Conclusion: MRI showed abnormal gyration patterns. 1H-MRS showed a decreased NAA/Cho ratio, the presence of lactate and an abnormal resonance at 1.11 ppm. Proton MRS can be a useful technique to detect cerebral metabolic abnormalities in neonates with the Zellweger cerebrohepatorenal syndrome.