A report of six cases of retroperitoneal rupture of the duodenum is presented. A high index of suspicion is necessary to enable early diagnosis to be made and appropriate treatment carried out. Early treatment will prevent the extremely rare, but at present uniformly fatal complication of gas gangrene. Plain X‐ray and Gastrografm studies may kelp to elucidate the situation in particular cases, but are no substitute for repeated careful abdominal examination. It is suggested that large doses of penicillin be employed where possible in the management of these cases, in addition to such antibiotic therapy as may be expected to be effective against the usual Gram‐negative bowel flora.