The proliferation and collagen synthesis of keratocytes during corneal wound healing after alkali-burn were investigated using 3H-thymidine or 3H-proline autoradiography. The effect of epidermal growth factor (EGF) on keratocytes was also examined. On day 1 after burn, the wounded stroma lacked keratocytes, and keratocytes at the periphery of the wound started to proliferate from the endothelial side. On day 7 and day 14, the population of keratocytes returned to normal. Collagen synthesis activity of the keratocytes was observed from day 7 through day 56, with the highest activity on around day 21. After day 14, keratocytes at the site of epithelial reopening or ulceration started to proliferate again. In the early stage of wound healing more keratocytes incorporated H-thymidine in eyes treated with EGF than those treated without EGF, suggesting that EGF may stimulate the proliferation of keratocytes in the early stage of wound healing.