To report the incidence of early allograft rejection after Descemet membrane endothelial keratoplasty (DMEK), that is, transplantation of isolated Descemet membrane with its endothelium. The first series of 120 eyes of 105 patients operated on for Fuchs endothelial dystrophy or pseudophakic bullous keratopathy, with an average 2 years of follow-up after 9.0- to 10.0-mm-diameter DMEK, enrolled in our study. During the entire study period, only 1 of the eyes showed any signs of a cellular immune response to the Descemet graft. A 76-year-old patient presented with discomfort, reduced visual acuity to counting fingers, corneal decompensation, and a Khodadoust line in the central cornea 4 months after (decentered) DMEK. Intensified topical corticoid therapy resulted in a complete visual recovery to 20/25 (0.8) within weeks. A "classic" allograft rejection (with an appearance similar to that after penetrating keratoplasty) can occur after DMEK. However, compared with the earlier (endothelial) keratoplasty procedures, DMEK may be associated with a lower rejection rate of ≤ 1%, despite transplant diameters of ± 9.5 mm. The apparent immune tolerance in DMEK may result from either less "upregulation" or more "downregulation" of the immune system.