Six carcinoid tumors of the small intestine were studied histologically. In three cases, a very small tumor had caused obstruction by a kinking process which was intrinsic within the bowel wall and was apparently produced by lateral submucosal tumor growth with traction on an underlying adherent muscularis. Hypertrophy of the muscularis and serosal fibrosis were contributory factors and possibly were related to tumor hormone production. The phenomenon was thought to depend on the interaction of several unusual features of the carcinoid tumor and so may be specific for this type of neoplasm. The tumor was concealed by the kink in these cases so that its presence was not suspected at surgery. Unless this gross appearance is recognized at surgery, the opportunity for definitive therapy with wide mesenteric resection may be missed.