BACKGROUND: CREST (Calcinosis, Raynaud's phenomenon, Esophageal dysmotility, Sclerodactyly and Telangiectasias) syndrome has been rarely associated with other malignancies (lung, esophagus). This is the first report of a primary adenocarcinoma of the third portion of the duodenum in a patient with CREST syndrome. CASE PRESENTATION: A 54-year-old male patient with CREST syndrome presented with colicky postprandial pain of the upper abdomen, diminished food uptake and a 6-Kg-body weight loss during the previous 2 months. An ulcerative lesion in the third portion of the duodenum was revealed during duodenoscopy, with a diagnosis of adenocarcinoma on biopsy specimen histology. The patient underwent a partial pancreatoduodenectomy. No adjuvant therapy was instituted and follow-up is negative for local recurrence or metastases 21 months postoperatively. CONCLUSION: CREST syndrome has been associated with colon cancer, gastric polyps, familial adenomatous polyposis (FAP) syndrome and Crohn's disease; however, this is the first report of a primary adenocarcinoma of the duodenum in a patient with CREST syndrome. However, any etiologic relationship remains to be further investigated.