(17–19) Alternatively, NAD(P)H oxidase activity and Nox1/Nox2 mRNA levels were increased in the lungs of fetuses with CDH, whereas SOD1, SOD2 and catalase mRNA levels were decreased.(20) Because iron distribution and metabolism are central to the initiation of oxidative stress (Fenton reaction),(21–23) we decided to analyse the nitrofen-induced CDH model from the viewpoint of iron, especially catalytic Fe(II), which can be visualized with recently developed fluorescent probes, RhoNox-1 and HM-RhoNoxM.(24–28). The gene discussed is SOD2; the disease is congenital diaphragmatic hernia.