The global COVID-19 health and economic crisis has forced people to adopt challenging rules of social distancing and self-isolation. Health care staff has been advised to change working routines to keep themselves and their patients safe. Radionuclide therapy has had an increasing role in clinical practice. Most therapeutic radionuclide procedures have applications in oncology. Cancer patients are an especially fragile and vulnerable population with higher risk due to co morbidities and immunosuppression. COVID-19 is another risk that must be considered in treatment planning. Therapeutic, prophylactic, and supportive interventions may require changes for these patients. The most common radionuclide therapies involve patients with differentiated thyroid cancer (DTC) who need radioiodine therapy (RAI), patients with neuroendocrine tumours (NETs) who need peptide receptor radionuclide therapy (PRRT), patients with hepatocellular carcinoma (HCC) who need therapy with radiolabelled microspheres, and patients with prostate cancer and bone metastasis who need radionuclide palliative therapy. If infected, cancer patients could be at a higher risk for serious COVID-19 disease. Treatment decisions for thyroid cancer and NETs are challenging in this environment. Any decision to postpone therapy must be carefully considered, balancing risks and benefits. A risk of worsened prognosis due to delayed or suboptimal cancer treatment must be weighed against the risk of severe COVID-19 illness.