A review was performed of the 37 cases of malrotation of the intestine which occurred in previously healthy children during a 12-year period. There were 33 patients (89%) younger than eight weeks of age, with 17 patients (46%) aged less than one week. Symptoms included bilious vomiting in 36 patients (97%) and constipation in 33 patients (89%). On initial examination, 35 patients (95%) appeared to be well (including 23/25 patients [92%] with volvulus of the midgut), and 28 patients (76%) exhibited no abnormal physical findings on abdominal examination (including 15/25 patients [60%] with volvulus of the midgut). In all, 25 cases (68%) of malrotation were accompanied by volvulus of the midgut; in 21 of these cases, torsion of the bowel was greater than or equal to 360 degrees. There were four patients (11%) with gangrenous bowel requiring surgical resection. The mortality rate associated with this disorder was 5%; both patients who died were neonates with volvulus who presented in shock and had extensively gangrenous bowel. Malrotation of the intestine usually presents in the young infant, is almost always associated with bilious vomiting, and is commonly accompanied by few if any abnormal physical findings suggestive of a serious underlying intraabdominal disease process. An emergent radiographic contrast study of the upper gastrointestinal tract should be performed to delineate the anatomy of the proximal bowel in all young infants with bilious vomiting.