Ectopic production of CRH by a medullary thyroid carcinoma or its metastases is a rare cause of ectopic Cushing's syndrome (ECS). We report a 45-year old male with medullary thyroid carcinoma (MTC), who, 24 years following the initial diagnosis, presented with clinical and biochemical evidence of an ACTH dependent Cushing's syndrome. Rapid deterioration of his clinical condition and elevated cortisol levels were observed. Computed tomographic imaging of the abdomen revealed extensive liver metastases. The patient underwent fine needle aspiration biopsy of a liver lesion and immunohistochemistry showed that the cells expressed calcitonin, carcino-embryonic antigen and synaptophysin. Further analysis revealed that the material also expressed CRH. This is an unusual case of a CRH-secreting liver metastasis from a medullary thyroid carcinoma 24 years after the initial diagnosis of MTC.