Endocrinopathies are common complications following cancer therapy and may occur decades later. We present a case of 37 year old lady with a background of chronic myeloid leukaemia (CML) which was treated with sibling allogenic stem cell transplant and total body irradiation in 2002. She was noted to have elevated calcium levels with raised PTH 10 years later. In view of young age, she underwent genetic screening for MEN1 through buccal swab as her lymphocytes were not suitable due to stem cell transplant from sibling, which was negative. She was then diagnosed with primary hyperparathyroidism as a complication of total body irradiation. During the investigations, she was noted to have a sub-centimetre benign looking thyroid nodule which on repeat ultrasound increased in size to 2.8 cm and showed increased central vascularity (U3). She subsequently had a fine needle aspiration twice which showed hyperplastic nodule consistent with benign cytology (Thy2) both times. However, in view of previous CML treated with irradiation, she underwent elective hemithyroidectomy in addition to parathyroidectomy. Her histology showed left inferior hypercellular parathyroid and encapsulated angioinvasive follicular carcinoma. She became normocalaemic post-surgery but in view of follicular carcinoma, she underwent completion thyroidectomy with subsequent radioiodine treatment. This case highlights many important learning points. First, whole body irradiation is associated with hyperparathyroidism which is lesser known long term complicationand therefore, it is important to monitor calcium levels annually in these patients. In addition, irradiation also increases the risk of secondary malignancies including thyroid neoplasms. There should be high index of suspicion for further investigations of thyroid nodules in such cases. In addition, it is important to remember that blood samples could not be used for DNA testing in patients with stem cell transplant and buccal swabs, although not gold standard could be used as an alternative.