We present a case of primary malignant pylorus neoplasia, emphasizing its rarity, the difficulty of diagnosis and the importance of an adequate prepare before the endoscopic procedure. Literature shows that tumors compromising the first, third and fourth segments of duodenum are rare, especially those of the pyloric area, representing only 0.35% of all malignant tumors of the gastrointestinal tract. Adenocarcinoma is the most common histological type, representing 50% of all malignant neoplasias at this site. The most common symptoms are weight loss, nausea, vomiting, abdominal pain, abdominal mass, sudden changes in intestinal habits and iron deficiency anemia secondary to chronic intestinal hemorrhage. Survival after five years is only 18%. We report a case of a seventy-one year-old male referring early satiety, epigastric pain, retrosternal burning and dyspepsia, with unspecific results in complementary exams, since complete gastric emptying was not achieved. As symptoms worsened, the patient was submitted to laparotomy, with identification of gastric dilation and severe pyloric stenosis, macroscopically suggesting malignancy. The chosen procedure was a subtotal gastrectomy. Adjuvant radiotherapy and chemotherapy were not used. The patient is been followed-up without tumor recurrence so far.