1H NMR spectroscopy of brain extracts was used to investigate the metabolic changes that take place during development of the neonatal rat brain. Data were obtained over the range 1-21 days. The concentration of N-acetylaspartate rose by a factor of 9 during this period, the most rapid rise occurring after day 9. The total creatine concentration rose from days 1-21, with a large increase between days 1 and 5. Taurine concentration rose until day 5, then fell from days 5-21. The concentration of choline-containing compounds fell during the 21 day period. The results are discussed in relation to brain development and conventional biochemical data. A major conclusion in relation to spectroscopy of children is that interpretation of changes seen in disease will require adequate data from age-matched controls.