Studies of the aetiology of diverticular disease of the colon have been focused on intraluminal pressure for almost three decades. It is only relatively recently that the mechanical properties of the wall of the colon have been examined. The tensile strength and elasticity of the colon decline with age and this is the most marked in the left colon which is the narrowest and thickest part. This review discusses the case that the mechanical properties of the bowel wall are key factors in the development of diverticular disease. The potential role of high fibre diets in reducing the pressure changes which may stress the colon wall in this disease is also considered.