OBJECTIVE: The objective of this study is to determine whether irradiance levels of phototherapy (PT) devices in Dutch neonatal intensive care units (NICUs) increased between 2008 and 2013. STUDY DESIGN: Irradiance of all types of PT devices, used in combination with incubators, was measured with a Dale 40 Radiometer (Fluke Biomedical, Everett, WA, USA) in all 10 Dutch NICUs. RESULTS: Irradiance increased in seven NICUs. Median (range) irradiance increased from 9.7 (4.3-32.6) to 16.4 (6.8-41) mu W cm(-2) nm(-1) for 24 overhead devices (P=0.004) and from 6.8 (0.8-15.6) to 22.3 (1.1-36.3), mu W cm-2 nm(-1) for 12 underneath devices (P=0.014). Five light-emitting diode (LED)-based devices were used in 2013 and one in 2008. The mean distance between overhead PT device and infant decreased by 9 cm (P <0.001). Significantly more devices delivered minimal (10 mu W cm(-2) nm(-1)) recommended irradiance levels (80 vs-45%; P=0.002). CONCLUSION: Irradiance of PT devices still varies, but has markedly improved since 2008 due to shorter distances between PT device and infant, and introduction of better performing LED -based devices.