INTRODUCTION:Medullary thyroid cancer(MTC) is a type of thyroid cancer of neuroendocrine origin. It occurs in both heritable and sporadic forms. It originates from the parafollicular "C Cells" secreting Calcitonin and Carcino embryonic antigen(CEA). Conventional radiographic techniques such as CT SCAN, MRI, AND Ultrasonography are used to detect recurrence following total thyroidectomy. However metastatic disease frequently escapes from above modaltits even in the presence of increased serum calcitonin levels

CASE REPORT:– We report a case of Medullary Thyroid Carcinoma in 24 year old male who under treatment of MTC with metastasis came with c/c of diarrhoea.

CONCLUSION:–Diarrhoea in MTC is though very rare do occur in some patients but what causes the diarrhoea is not clearl understood.