We used preoperative ultrasonography to study a case of perforated diverticulosis of an ileocecal lesion, and identified lipohyperplasia of the ileocecal valve and a peridiverticular abscess characterized by its remarkable appearance in sonographic images. The circumference of the submucosal layer of the valve was markedly thickened and contained speckled hypoechoic areas within a highly hyperechoic zone. Comparison with the resected specimen suggested that the hyperechoic zone was derived from the irregularly deposited adipose tissues of the valve. On the other hand, the peridiverticular abscess contained a triangular hypoechoic area with an irregular margin at the site of mesenteric attachment of the ascending colon. We believe this to be the first case of lipohyperplasia of the ileocecal valve reported in Japan. We describe preoperative findings and compare them with those of the resected specimen.