Aim Coronectomy of mandibular third molars deemed to be at risk of inferior alveolar nerve injury (IANI) has become an increasingly common treatment modality. The primary principle of the procedure is the removal of coronal tissue and retention of vital root(s) with non‐inflamed pulpal tissue to be surrounded by normal bone. Oncological treatment is currently considered a contraindication for coronectomy due to the theoretical assumption that there is an increased risk of infection from non‐vital coronectomy roots in patients whose oncological disease can result in the development of secondary or acquired immunodeficiency. Additionally, patients with oncological conditions who have undergone head and neck radiotherapy (RT) or received bone modulating agents could be at risk of osteonecrosis either following coronectomy or future root retrieval. This mini case series aims to investigate the outcomes following coronectomy concentrating on oncology patients. Methods Between 2011 and 2017, seven patients prior to commencing head and neck RT or chemotherapy underwent coronectomy of nine mandibular third molars (M3Ms). Results Clinical and radiographic follow up for a mean of 15 months (range 3–48) had shown healing with no report of persistent pain or infection. Fifty‐six per cent of roots demonstrated migration radiographically. No cases required root retrieval or experienced post‐operative IANI or osteonecrosis of the jaw. Conclusion This mini case series provides some early insight into the use of coronectomy in oncology patients, however, requires a larger patient population and longer follow up.