Primary anaplastic carcinoma is a rare variant of small intestinal cancer. Most reports of primary anaplastic carcinoma of the small intestine are isolated case reports, therefore the clinicopathological features, therapeutic management, and surgical outcome of this tumor type remain unclear. This review analyzes the available clinical characteristics of primary anaplastic carcinoma of the small intestine and investigates key differences from differentiated adenocarcinoma of the small intestine. A Medline search was performed using the keywords 'small intestine' and 'anaplastic carcinoma' or 'undifferentiated carcinoma'. Additional articles were obtained from references within the papers identified by the Medline search. The literature revealed a poor prognosis for patients who underwent surgical resection for anaplastic carcinoma of the small intestine, which gave a 3-year overall survival rate of 10.8% and a median survival time of 5.0 mo. The literature suggests that anaplastic carcinoma is markedly more aggressive than differentiated adenocarcinoma of the small intestine. Surgical resection with the aim of complete tumor removal provides the only beneficial therapeutic option for patients with anaplastic carcinoma of the small intestine, because chemotherapy and radiation therapy have no significant effect on the rate of survival. However, despite complete tumor resection, most patients with anaplastic carcinoma of the small intestine are at great risk of disease recurrence. Multicenter clinical trials are expected to provide additional therapeutic strategies and establish the efficacy of multimodality adjuvant therapy. This report also highlights the importance of a systematic diagnostic approach for anaplastic carcinoma of the small intestine.