One hundred consecutively submitted corneas removed by penetrating keratoplasty were studied histologically to determine the frequency in which eosinophils are found. In 20 corneas eosinophils occurred in densities ranging from 0.2 to more than 50 per high power field (HPF), and accounted for 1.5% to 100% of the total leucocytes counted. More than half of the corneal specimens containing eosinophils, including six of seven corneas having the highest eosinophil concentrations, were failed grafts. Because the concentration of eosinophils was in many cases beyond that attributable to non-specific vascular permeability, the existence of eosinophil chemotaxic substances in the cornea is postulated.