BACKGROUND Our purpose was to evaluate the sterility of organ-cultured human donor corneas at the time of surgery. METHODS We studied 603 organ-cultured corneas. Of these 603 corneas, 409 (68%) were grafted and 69 (11%) were contaminated during storage. RESULTS Contamination during preservation was either bacterial (65%) or fungal (35%). None of the tested antibiotics were effective against all of the 45 isolated bacteria. The risk of contamination decreased with death-to-organ culture time (P=0.008) and was higher for corneas excised in situ than for those enucleated (P=0.02). Corneoscleral rims were sterile in 99.3% of the grafted corneas. Deswelling media were sterile in 100% of cases. A 19- to 53-fold decrease in the percentage of rim contamination was assessed with organ culture as compared with hypothermic storage (previous studies, P < 0.0001). CONCLUSIONS These results demonstrate the benefit of organ culture over hypothermic storage, because it allows contaminated tissue to be discarded.