A retrospective analysis of 110 longitudinal septa ov the vagina which were seen at the Hotel-Dieu in Paris, demonstrated the following features: They were well tolerated and were discovered by chance in nearly 60% of cases, causing symptoms in 40% of cases. These symptoms were: dyspareunia, apareunia, haemorrhage at the first act of intercourse and more recently signs connected with the increasing use of tampons for the periods. They were complete in 49% of cases and incomplete in 51% of cases mainly in the upper part of the vagina. They were associated: in 26% of cases with a bicornuate-bicervical uterus, in 64% of cases with a septate uterus, the septum being total in 54% of the cases, in almost 10% of cases there was either a normal uterus or communicating uteri. There were fewer than 1% of normal uteri above septa that included the cervix and the vaginal vault. Clinical study of these malformations of the uterus and the vagina lead one to be able to make a hypothesis about the embryology: the fusion of the Müllerian canals and then the absorption of the septum where they join starts at the level of the isthmus. All morphological abnormalities of the uterus occur between the 55th and the 68th day of fetal life. The treatment is surgical, which is simple but has to be carried out very carefully. It consists of division or removal of the septum and should be done when the symptoms make it necessary, or during delivery when it gives rise to a dystocia or to a tear, which occurs but rarely.