The evolution and general principle of the Erlangen magnetic ring colostomy device are described and its practical use illustrated by reference to a personal series of 22 patients treated with the device. Analysis of the functional results obtained in 13 of these cases, who were assessed after at least 3 months' trial, shows that only 3, or at most 4, could be considered to have achieved worth-while continence, but there are grounds for believing that these results might be improved a little by more stringent selection of patients for the procedure and by employing a more meticulous technique for implanting the rings.