Medullary thyroid carcinoma associated diarrhoea can be disabling. A 75-yr-old man with metastatic medullary thyroid carcinoma and refractory diarrhoea is described. Subcutaneous administration of the somatostatin analogue, octreotide, 100 micrograms thrice daily, resulted in a sustained improvement in diarrhoea and disappearance of faecal incontinence without reducing calcitonin levels. Octreotide therapy should be considered as symptomatic treatment for otherwise refractory diarrhoea associated with medullary thyroid carcinoma.