Purpose To investigate the influence of graft storage time on corneal allograft survival in high-risk and low-risk patients.Design Comparative retrospective n onrandomized clinical trial.Participants Overall,193patients with 210corneal allografts were classified as high r isk or low risk for corneal allograft rejection on the basis of r ecipient corneal neovas-cularization and number of ipsilate ral transplants.Methods Data from 3groups were evaluated.The first group re-ceived fresh(no storage in culture medium)corneas,the second received corneas of donor sto rage time less than 7days in minimum essential medium(MEM)at 37°C,and the final group received corneas sto red in MEM longer than7days.Recipients were analyzed for development of im-mune rejection according to storage time of the corneal tissue.Corneal allograft survival rate was determined with Kaplan-Meier survival analysis.The log-rank test was used to determine statistical significance.Main outcome mea-sures Risk of reversible and irreversible allograft rejection in corneas stored at various intervals in high-corneal and low-corneal transplant patients.R esults High-risk corneal allograft recipients had a signific antly prolonged allograft survival when the tissue was stored f or 7days or greater,compared with recipients receiving fresh tissues.Patients at low risk of corneal allograft reje ction also showed a ten-dency for prolonged survival,although not statistically significant (P=0.06).Conclusions Storage of corneal tissue may reduce the frequency of allograft rejection,es-pecially in high-risk patients. Purpose To investigate the influence of graft storage time on corneal allograft survival in high-risk and low-risk patients. Design Comparative retrospective n onrandomized clinical trial. Participants Overall, 193patients with 210 corneal allografts were classified as high r isk or low risk for corneal allograft rejection on the basis of r ecipient corneal neovas-cularization and number of ipsilate ral transplants. Methods Data from 3groups were evaluated.The first group re-ceived fresh (no storage in culture medium) corneas, the second received corneas of donor sto rage time less than 7 days in minimum essential medium (MEM) at 37 ° C, and the final group received corneas sto red in MEM longer than 7 days. Recipients were analyzed for development of im-mune rejection according to storage time of the corneal tissue. Corneal allograft survival rate was determined with Kaplan-Meier survival analysis. The log-rank test was used to determine the significance significance. Main outcome measures-of-reversibl e and irreversible allograft rejection in corneas stored at various intervals in high-corneal and low-corneal transplant patients. Results High-risk corneal allograft recipients had a significant prolonged allograft survival when the tissue was stored f or 7 days or greater, compared with recipients receiving fresh tissues. Patients at low risk of corneal allograft reje ction also showed a ten-dency for prolonged survival, although not statistically significant (P = 0.06) .Conclusions Storage of corneal tissue may reduce the frequency of allograft rejection, es-pecially in high-risk patients.