Following a radiation emergency, children may be internally contaminated by the radionuclide(s) involved. Timely assessment of the contamination informs the need for medical treatment for those persons who had significant intakes and reassures those whose intakes are not a medical concern. In vitro bioassay reference values for children of all ICRP age groups are derived for 30 contamination scenario/radionuclide combinations involving 13 radionuclides. These bioassay values are derived from an intake that leads to a 70‐y committed effective dose of 50 mSv or a 30‐d RBE-weighted absorbed dose to the lungs of 0.2 Gy-Eq, depending on which criterion is more strict. These values are presented in a collection of lookup tables that can be used directly as references.