Near-infrared spectroscopy is a new technique for noninvasive monitoring of tissue oxygenation and haemodynamics. Quantitative measurements can be made of oxyhaemoglobin, deoxyhaemoglobin, oxidized cytochrome and various haemodynamic indices. This technique is likely to prove increasingly valuable for: cotside monitoring brain oxygenation and haemodynamics in babies; investigating the mechanisms of damage to the brain; according the results of treatment; and assigning long-term prognosis.