Protection of the environment against the harmful effects of ionising radiation was mentioned in both ICRP Publication 26 (1977) and Publication 60 (1991), but it was at the time assumed that ‘if man is adequately protected then other living things are also likely to be sufficiently protected.’ A decade later, Publication 91 (2003) recognised that the ‘Impact of Ionising Radiation on Non-human Species’ was an independent topic worthy of attention. It was in this publication that the ICRP first explicitly addressed ethical issues. It discussed the importance of different philosophical worldviews regarding the environment, such as anthropocentrism and biocentrism, and identified some internationally agreed upon ethical principles relevant for radiological protection of the environment, namely sustainable development, conservation, preservation, maintenance of biological diversity, environmental justice, and human dignity. These partly overlap with the core ethical values identified in Publication 138 (2018) on the ‘Ethical Foundations of the System of Radiological Protection’: beneficence/non-maleficence, prudence, justice, and dignity. The latter document does give a certain weight to environmental issues, but it does not clearly distinguish between questions of environmental health (the effects of environmental factors on human health) and environmental integrity (the effects of the same factors on non-human species and whole ecosystems). It is argued here that the ethics of (radiological) protection of the environment needs to be considered in its own right, even if it is not beyond the scope of Publication 138.