PURPOSE: To evaluate whether regional cerebral oxygenation (rSO(2)) by near-infrared spectroscopy correlates with central venous (SvO(2)) or internal jugular (SjO(2)) oxygen saturation, and whether changes over time (Delta) in rSO(2) (DeltarSO(2)) predict changes in SvO(2) (DeltaSvO(2)) and SjO(2) (DeltaSjO(2)). METHODS: The rSO(2) values were measured using the INVOS 5100 cerebral oximeter in children undergoing interventional cardiac catheterization and were compared with the oxygen saturation of analysed central venous and internal jugular blood samples. Changes over time (Delta) were calculated as the difference between the values before and after catheter intervention for rSO(2).(DeltarSO(2)), SvO(2).(DeltaSvO(2)) and SjO(2).(DeltaSjO(2)). Simple regression and Bland-Altman analysis were performed. Data are presented as median (range). RESULTS: Sixty patients aged 4.3 (0.2-16.0) years were investigated. A closer correlation was found between rSO(2) and SvO(2) (r=0.728, P<0.0001) than between rSO(2) and SjO(2) (r=0.665, P<0.0001). The bias between rSO(2) and SvO(2).(SjO(2)) was 0.17% (-0.60%), with limits of agreement from -15.5% to 15. 9% (-18.6-17.4%). The sensitivity/specificity for DeltarSO(2) to indicate a fall in SvO(2) or in SjO(2) was 70.3%/65.2% and 68.6%/60.0%, respectively. CONCLUSION: Neither absolute values nor changes in rSO(2) using the INVOS 5100 allowed reliable estimation of SvO(2) or SjO(2) and their trends.