Proton magnetic resonance spectroscopy ('H MRS) is a non-invasive method to investigate brain metabolism in vivo. To evaluate the usefulness of 'H MR spectroscopy in the evaluation of normal developing brain, we examined 11 normal preterm newborns The range of postconceptional age (PCA) in this study was 35-39 wk. 'H MR spectoscopies were performed on GE 1.5 T SIGNA system. Image guided STEAM-Spectra were obtained from the occupital gray and parietal white matter (TR: 3000 msec, TE:30 msec, AVG: 48, NEX: 2, voxel size: 8cc). To characterize the difference of spectra between premature infants and adult brain, the data from this study were compared with our normal adult data(N=25, age 23-65). All the babies had peak resonances on their spectra which could be assigned to N-acetyl asparate(NAA), choline(Cho), creatine(Cr) and myoinositol(mI). Between 35 and 39 wk of PCA, both NAA/Cr and NAA/Cho ratios show a significant linear increase with increasing PCA. (Y=0.098X-2.78, p<0.05, Y=0.095X-2.91, p<0.05 in parietal white, Y=0.08X-2.14, p<0.05, Y=0.074X-2.13, p<0.05 in occipital gray matter, respectively). Cho/Cr and mI/Cr, in contrast, decreased by half. This study showed that the developmental increase of NAA could be related to normal outgrowth of brain during study period. Therefore we speculate that abnormal increase of NAA and the presence of abnormal metabolites, such as glutamate and lactate demonstrated in vivo using 'H MRS in preterm brain could predict poor outcome.