Introduction: Undifferentiated carcinoma of the esophagus (UEC) is an uncommon esophageal malignancy. Patient with UEC has a notably poor prognosis because of extensive metastasis despite at the early stage. A standard treatment regimen for UEC has not yet been established. 

Case report: We reported a case of undifferentiated carcinoma in a 46 years old male with a common chief complaint of progressive dysphagia accompanied by chest discomfort after meal and significant weight loss. Base on the history of illness, physical examination, imaging, and histopathology we concluded that the patient was diagnosed with undifferentiated carcinoma of the esophagus at the gastroesophageal junction. The patient received chemoradiotherapy of CDDP + 5-FU along with radiation, but declined the temporary gastrostomy as nutritional intervention. 

Conclusion: Undifferentiated carcinoma of the esophagus (UEC) is a rare neoplasm and often associated with locoregional recurrence and/or distant metastasis. Multidisciplinary involvement for the treatment of this disease is necessary to obtain a better outcome.