Background: Near-infrared spectroscopy (NIRS) is an upcoming clinical method for monitoring regional cerebral oxygen saturation (rScO 2 ) in neonates. There is a growing market offering different devices and sensors. Even though this technique is increasingly clinically applied, little is known about the similarities and/or differences in rScO 2 values between the different devices and sensors. The aim of this study was to compare the rScO 2 values obtained in (preterm) neonates with all available sensors of three frequently used NIRS devices. Methods: Fifty-five neonates admitted to our neonatal intensive care unit (NICU) were included in this study. rScO 2 was simultaneously monitored bilaterally with two different NIRS sensors (left and right frontoparietal) for at least 1 h. Then, the sensors were switched, and measurements were collected for at least another hour. results: We detected a rather close correlation between all investigated sensors from the three different NIRS devices, but absolute rScO 2 values showed substantial differences: BlandAltman analysis showed average differences from 10 to 15%. conclusion: Although the rScO 2 values correlated well between different NIRS sensors, sometimes there were substantial differences between the absolute rScO 2 values, which may complicate clinical application.