Catenins are cytoplasmic proteins associated with E‐cadherin, the prime mediator of cell–cell adhesion. Perturbation in any of these molecules results in altered intercellular adhesion, cell differentiation, and increased migration. In this study, the expression and cellular localization of catenins and E‐cadherin in inflammatory bowel disease were examined. The expression of E‐cadherin; α‐, β‐, and γ‐catenin; and p120 was evaluated immunohistochemically in 31 paraffin‐embedded colonic specimens from 21 patients with ulcerative colitis and Crohn's disease. Loss of normal membranous E‐cadherin and α‐catenin staining was detected at the mucosal edges around epithelial ulcerations in all cases of active ulcerative colitis and in 50 per cent of cases with active Crohn's disease. Reduced expression of p120 protein was also found at the margins of ulcerated mucosa in all cases of active ulcerative colitis and in 75 per cent of those with active Crohn's disease. There was a statistically significant correlation between the expression of E‐cadherin, α‐catenin and p120 and disease activity. There were no changes in β‐ and γ‐catenin expression in either ulcerative colitis on Crohn's disease. These findings indicate that altered expression of E‐cadherin, α‐catenin, and p120 occurs during mucosal ulceration in inflammatory bowel disease. These changes may be involved in promoting cell migration during epithelial restitution of the gastrointestinal mucosa. © 1998 John Wiley & Sons, Ltd.