In vitro viability of the endothelium of corneas stored in organ-culture medium is longer than in other storage techniques. This article reports on the clinical results of 20 penetrating keratoplasties performed using corneas stored for > 4 weeks in organ culture. Seventeen of the procedures were elective and three were emergencies. Mean preservation time was 35.6 +/- 7 days (mean +/- SD) and mean follow-up was 16.2 months. During preservation, an endothelial cell loss of 10% was noted. Seventeen grafts remained transparent, and three failed between 3 and 24 months postoperatively. Mean endothelial cell density was 2,153 +/- 372/mm2 at 4 months and 1,854 +/- 390/mm2 at 12 months. Central pachymetry was 548 +/- 53 microns at 4 months and 528 +/- 57 microns at 12 months after surgery. Corneas stored for up to 48 days in organ culture can be used in elective as well as in emergency procedures.