Routine use of cryosurgery in a series of 200 cataract extractions resulted in a marked increase in the incidence of irreversible corneal edema when compared with a series of 900 deliveries by conventional methods (increase from 0.66% to 4¼%). This is presumably due to inadvertent freezing and lysis of a critical number of endothelial cells. These clinical observations are consistent with laboratory findings of other workers who induced irreversible corneal edema in rabbits by surface freezing techniques. Further research appears indicated before cryosurgery can be routinely adopted as a safe method of cataract extraction. Until such time caution is urged.