The following cases of congenital malformation of the rectum and anus which I have chosen as a subject for my Thesis have been treated at the Liverpool Childrens' Infirmary during the last four years. I propose first to refer briefly to the classification of the cases and to give some statistics as to the frequency of the condition. I will then give the notes on the various cases, and will afterwards enter at some detail into the treatment. Finally in commenting on the Post Mortem Examiinations I shall give a brief sketch of the development of the parts involved.