OBJECTIVE To evaluate whether the organ culture method for human cornea preservation may be applied to corneas stored for several days at 4 degrees C. METHODS The cell density, viability, and morphology of corneal endothelium were examined in 140 human corneas stored at 4 degrees C for the minimal time required for transport to the bank and for the preliminary controls of cornea status (1.6 +/- 1.1 days) and in 46 corneas preserved at 4 degrees C for 6.1 +/- 1.9 days in Optisol-GS. The evaluation was repeated after 19.7 +/- 9.1 days of incubation at 31 degrees C in a culture medium containing 2% newborn calf serum. RESULTS After the hypothermic storage the corneal endothelium had a mean density of 2475 +/- 159 cells/mm2 without significant difference between the short and the long-term incubation. Several corneas of the two groups showed signs of endothelium degeneration and were positive to trypan blue test. After the incubation at 31 degrees C, the corneas with endothelial degeneration decreased by 52.2% and those positive to trypan blue decreased by 21.7%. Polymorphism (enlarged endothelial cells) increased from 9.6% to 14.5% of the corneas. The remodeling of the endothelium led to a 6.7% decrease in cell density. These results were similar after short-term and long-term storage at 4 degrees C. CONCLUSIONS Organ culture was effective in improving corneal endothelium when the hypothermic storage was prolonged to the upper temporal limit for this procedure (7-10 days). These results may encourage the possibility of an eye bank to allocate the available cornea pool, thus decreasing the risk of discarding precious material.