This paper studies the clinical results of 150 cases of penetrating keratoplasties using corneas preserved in McCarey-Kaufman media and Na Hyaluronate (Healon®) at the time of surgery. The 150 transplants had been performed between July 1980 and January 1982 by the author. A series of 30 grafts done between 1978 and 1979 by the staff of a medical center in which the author was one of the surgeons, was used as a control for the use of Healon®; all grafts had been preserved in MK media. Results showed 96.6% clear grafts during the first postoperative week and 97.3% clear grafts at the end of 6 months. There were five cases of primary tissue failure, but no cases of infection related to the MK-stored corneas. The use of Healon® facilitated the surgical procedure and protected the endothelium of the graft. This was evident by the extreme transparency of the graft postoperatively and its rapid return to normal thickness when compared to control grafts. No instances of inflammatory reaction to Healon® were detected, but a tendency to increased intraocular pressure was noticed if large amounts of the substance were injected into the eye. It is concluded that MK-stored corneas protect the endothelium and expand the viability of graft endothelium. The additional use of Healon® at the time of surgery facilitates the surgical procedure and provides additional protection to the endothelium of the graft.