The spermatic cords of 24 representative marsupial species have been examined for the presence of a rete mirabile. In the great majority, a well-developed rete, consisting of many parallel arteries and veins enclosed within fibrous and cremasteric muscle sheaths, was present, and it is suggested that this finding is of some taxonomic value, since no similar structure has been observed in eutherian mammals (Harrison 1949). The functional significance of this rete mirabile is discussed.