The solid-sphere test was used to measure the strength of the anal sphincter. A plastic sphere 2 cm in diameter was inserted into the rectum. The plastic sphere was stepwise loaded. The patient was asked to contract his sphincter and try to keep the sphere inside the rectum. The maximal strength was defined as the force needed to draw the sphere through the anus. In continent persons the force needed was above 7 N, in persons with partial incontinence between 5 and 7 N, and in persons with total incontinence below 5 N. A clear difference between continent and totally incontinent persons was found. The solid-sphere test is simple, cheap, and of great value in examination of faecal incontinence.