The form of the rete testis has been investigated in all members of two families of possums, the Acrobatidae and the Burramyidae. A simple rete like that found in members of many other families of marsupials was seen in Distoechurus pennatus, one of the two species of acrobatids. The rete in the six species of burramyids was only slightly different from that seen in Distoechurus. In Acrobates pygmaeus, the other acrobatid, the rete was found to be most like the horseshoe-shaped rete found in a phalangerid and in macropodids. On the basis of the form of the rete testis, Acrobates and Distoechurus do not appear to be closely related.