True lipomas arising primarily in the mesentery of the small intestine are extremely rare. In 1921 Wahlendorf (15) reviewed the literature and collected 132 retroperitoneal lipomas. Nineteen of these involved the mesentery of the small gut. The published data in the older literature are meager, however, and in some instances it is impossible to ascertain whether the tumors were true lipomas and whether they originated in the mesentery or involved it secondarily by extension from the adjacent retroperitoneal region. Considering only cases in which total or partial surgical extirpation was performed, Schmid (10) culled from the literature up to 1921 records of only 6 lipomas which arose primarily in the mesentery of the small intestine, In addition, he found 76 retroperitoneal lipomas and liposarcomas, as well as 23 mesenteric extensions from the retroperitoneal region. Only 4 of these are said to have been lipomas extending into the mesentery of the small intestine. From 1922 up to 1948, only 19 additional cases of lipoma arising in small intestinal mesentery were reported (1, 2, 3, 7, 8, 9, 11, 12, 14, 17). The rarity of mesenteric lipoma and the desirability, from the point of view of prognosis, of distinguishing it sharply from retroperitoneal lipoma with secondary extension into the mesentery warrant the following case report and the subsequent discussion of the subject. Case Report A 29-year-old white male was admitted for the first time to the Mt. Alto Veterans Hospital on Feb. 11, 1948, complaining of abdominal cramps, nausea, and vomiting. Past History: At the age of eight the patient underwent an exploratory laparotomy for a similar episode. An appendectomy was performed at that time and his parents were informed that there was some malrotation of the colon. Occasional bouts of vomiting were experienced up to the age of sixteen. Present History: The patient had been in good health until the afternoon prior to admission, when he began to “feel not up to par.” At 7:30 that evening, one and a half hours after a heavy dinner, he had one formed bowel movement, followed at ten-minute intervals by two loose, gray, oily stools. Shortly thereafter he became nauseated and vomited repeatedly, though there was no hematemesis or melena. At 10:00 p.m. he began to suffer from abdominal cramps in the left upper quadrant, lasting for only half a minute but increasing progressively in frequency. The vomiting subsided during the following morning, but the cramps continued to recur every five or ten minutes. Physical Examination: The patient was obese (229 lb.) and evidently in acute distress. No abdominal masses could be palpated. On auscultation, sounds characteristic of obstruction occurred synchronously with the cramping pains. Temperature was normal. A survey film of the abdomen revealed several distended loops of small bowel in the left upper quadrant. Response to conservative therapy was prompt, and the acute phase rapidly subsided.