The purpose of this review is to highlight new developments during the past year regarding diagnosis and clinical features of inflammatory bowel disease. Endoscopy remains the cornerstone for diagnosis and evaluation of ileocolonic inflammatory bowel disease. In ulcerative colitis, recent studies have challenged the concept of a continuous and homogeneous inflammatory process with constant rectal involvement: Patchy inflammation and rectal sparing were reported in treated ulcerative colitis, and frequent cecum and appendiceal orifice skip lesions were confirmed. Cross-sectional imaging techniques usefully complement endoscopy by assessing whole-bowel thickness and detecting abscesses and fistulae. Furthermore, echo Doppler ultrasound is able to measure mesenteric blood flow, which is increased in active inflammatory bowel disease and seems to parallel inflammatory disease activity. Osteopenia, which affects approximately half of patients with inflammatory bowel disease, can be detected by dual-energy x-ray absorptiometry and prevented. Hyperhomocystinemia, a predisposing factor for thrombosis, seems to be more frequent in inflammatory bowel disease, and can be corrected by folate supplementation. The concept of an aggressive, penetrating form of Crohn disease with early postoperative recurrence as opposed to a more indolent, nonpenetrating form of the disease, with later recurrence, was recently challenged. The most significant predictor of the risk of malignancy in inflammatory bowel disease remains the presence of dysplasia in colonic biopsy specimens. A dysplastic polypoid lesion or mass is a strong predictor of cancer but should be distinguished from the dysplasia inherent in a coincident sporadic adenoma. Curr Opin Gastroenterol 2000, 16:329-336 (C) 2000 Lippincott Williams & Wilkins. Inc.