The authors describe the clinical and pathologic findings in 29 patients with injuries from motor vehicle accidents. The seromuscular tear (SMT), the hallmark intestinal injury of the seatbelt syndrome, is an unambiguous lesion similar in all segments of bowel and is caused by a tear that separates the inner muscularis from the submucosa. It is characterized by (1) a wedge that strips the submucosa from the inner circular muscle; (2) a bending retraction of the torn muscularis toward the uninvolved bowel wall; (3) mucosal-submucosal fold effacement, causing the mucosa-submucosa bridge spanning the tear to become paper thin; and (4) the vulnerability of this bridge to ischemia that in 35% of the tears studied culminated in incipient or frank perforations and/or gangrene. Large SMTs, particularly the circumferential degloving type, are most prone to develop these complications. These findings militate against the idea that the SMT is a trivial lesion. The SMT occurred in 90% of patients in this report and accounted for 65% of all intestinal lesions. Seventy-three percent of the tears developed in the colon, and one third of all SMTs occurred in the sigmoid colon. Two thirds of all intestinal and mesenteric injuries clustered in three sites: the ileocecal region, the sigmoid colon, and the jejunum. Perforations were the principal lesion in the jejunum and SMTs at the other two locations. Ninety percent of patients experienced two or more intestinal lesions. This suggests the simultaneous action of different traumatic mechanisms on the bowel and its mesenteries in seatbelted persons who are in motor vehicle accidents.