The sustainability of radiation biology (radiobiology) is under threat in South Africa because of underdevelopment in the discipline, despite the fact that South Africa has been a user of radiation since radioactivity and X-rays were discovered. The widespread use of radiation in medicine, nuclear reactors, particle accelerators and other sophisticated nuclear facilities in South Africa makes it imperative that the interaction of radiation with biological systems is understood. For example, radiobiology is critical in radiation oncology and cancer treatment. Radiobiology is a distinctly biological science and its uniqueness and value should be highlighted to provide insight for authorities and other relevant parties. Regrettably, radiobiology has been largely neglected despite the importance of maintaining expertise and competence in this discipline. Many radiation-associated disciplines require radiobiology for their training and practice yet few radiobiologists are available nationally. The scientific community needs to be informed of the predicament of radiobiology in South Africa so that the situation can be addressed. Radiobiology is a scarce skill that needs to be developed to support South Africa’s mature radiation infrastructure. The country has too few radiobiologist training programmes and there is a lack of succession planning. Radiobiology is required for training and practice in a number of disciplines that use radiation, but, as a result of a shortage of qualified personnel, teaching of radiobiology has frequently been conducted by non-experts. To reinvigorate radiobiology in South Africa, a collective effort by government, academia, industry and allied professionals is required.