SUMMARY
Retention of host's Descemet’s membrane (DM) is an unusual complication in penetrating keratoplasty. Two cases of accidental retention of Descemet's membrane and posterior lamellaes of corneal stroma in penetrating keratoplasties, identified postoperatively as a retrocorneal membrane (RCM) are reported. In the first patient there was contact between the RCM and the donor's endothelial surface, ensuing graft failure. In this case, histologic examination confirmed the duplicated Descemet's membrane. In the second patient, the membrane has never in contact with the graft, which remained clear. However, the RCM became progressively opaque and the Nd: YAG laser was required to create a opening and improve the visual acuity. The ultrasonic biomicroscopy, used for the first time in such cases, identified the two layers of RCM: posterior stromal lamellaes and DM. Observations about the etiopatogeny, prevention and treatment of this surgical complication are made, which may lead to graft failure if not properly identified and treated. To the best of our knowledge, this is the first description of this surgical complication in the brazilian literature.