Background: Choroidal metastasis is a very rare clinical manifestation of thyroid cancer. Herein, we report on a patient with non-familial medullary thyroid carcinoma (MTC), who presented with choroidal metastasis. Case Report: A 63-year-old male patient with MTC presented with sudden loss of vision in his right eye for 1 month. The patient had a history of complete thyroidectomy and chemotherapy for disseminated MTC. Ophthalmological examination showed optic disc and choroidal metastases in the right eye and a small choroidal metastasis in the left eye. The patient was scheduled for external irradiation therapy for the ocular area but died 2 months after choroidal metastasis was diagnosed. Conclusions: Choroidal metastasis must be considered in MTC patients who develop loss of vision. This is a very rare clinical situation that generally occurs in the late advanced stages of the disease and carries a poor prognosis for these patients.