Summary Three hundred and ninety-three patients who had anal fissures were followed continuously for approximately five years. More than 44 per cent of them were cured nonsurgically within a four-to eight-week period. There was an 8 per cent complication rate, consisting of abscesses and fistulas, necessitating surgical treatment. The recurrence rate following healing was 27 per cent, but a third of these patients had recurrent fistulas that healed in response to further conservative treatment. The authors feel that conservative treatment of anal fissure is justified unless there is advanced anal stenosis.