This is a retrospective analysis of three patients who underwent mini DMEK for massive corneal hydrops in acute keratoconus. DMEK graft was trephined or trimmed according to the size and the shape of the gap in the patient’s Descemet membrane (DM). The grafts were inserted with a regular intraocular lens shooter and unfolded with use of intraoperative OCT. At the end of the surgery, the graft was attached to the posterior corneal surface by a small air bubble. Thereafter, anterior chamber was filled with 20% SF6 gas. All three patients (age 32+/-3 years on average) showed a rapid increase in uncorrected visual acuity from LogMAR 1.66 (+/-0.46) before mini-DMEK to the LogMAR 1.2 (+/-0.3) within six to eight weeks after mini-DMEK. The thickest corneal point within the oedematous cornea decreased in all three patients (1088+/-280[mu]m before surgery vs. 630+/-38[mu]m one week after surgery). One mini-DMEK failed in the first attempt. In this patient, the recipient DM was under strong tension and showed a pronounced dehiscence. Therefore, a small part of the recipient’s DM around the preexisting gap in DM was removed before a second mini-DMEK graft was placed successfully. The other two patients developed partial graft detachment within one to two weeks after surgery. However, the corneas of these patients were dehydrated to physiological levels after mini-DMEK, and despite partial detachment, there was no relapse of the hydrops. The authors conclude that mini-DMEK could be helpful in patients with larger defects and detachments of DM in very ectatic corneas in the acute phase of corneal hydrops in acute keratoconus. These patients may not be successfully treated by intracameral gas application alone or in combination with pre-Descemetal sutures. While the older methods showed a slow resolution of corneal oedema, the authors believe that the main reason for rapid dehydration in their patients is the DMEK graft. Further studies with control groups receiving intracameral gas alone may help to identify if DMEK graft is the reason for rapid recovery of corneal oedema.