We examined the glucose metabolism and ultrastructure of human corneas stored for 11 to 37 days in organ culture using a modified Eagle's minimum essential medium. Changing the media twice weekly provided a stable pH of 7.22 to 7.28 but the glucose concentration of the media decreased from 110 mg/100 ml to 30 mg/100 ml, and lactate concentration increased from 7 mg/100 ml to 84 mg/100 ml before media replacement. The initial rate of glucose uptake and lactate release averaged 149 mug/hr and 95 mug/hr, respectively, and the rates decreased approximately 50% by day 12. The glucose uptake rate stabilized between 40 and 60% of the original rate to day 37, but the lactate release rate decreased again at day 25 from 64 to 25%. The lactate/glucose ratio averaged 65 to 82% during the first 25 days of organ culture and 33 to 53% from days 28 to 37. Electron microscopy revealed that the endothelium formed a complete monolayer of normal appearing cells covering Descemet's membrane. Intracytoplasmic deposition of glycogen granules was present in endothelial, stromal, and epithelial cells.