Human cadaver corneas were obtained 10--12 h after clinical death, incubated in organ culture for 20--28 h and exposed 2, 4, 6, 8, 6, 4, and 2% DMSO successively for 10 min at each concentration. Endothelial cell damage was recognized by morphological alterations during reformation of a coherent cell sheat after expulsion of damaged cells. DMSO was found to cause latent cell damage at 31 degrees C. No cell damage was found at 4 degrees C when DMSO was dissolved in minimum essential medium (Eagle) plus Dextran or when DMSO was dissolved in human albumin plus sucrose. DMSO was found to be toxic at 4 degrees C in pure serum and in Dulbecco's medium.