We produced alkali burns (1.5 N NaOH) in the right eyes of 63 mice. Three weeks later the left eye of each mouse was similarly burned. All eyes were followed up weekly for 4 weeks after the burn and were graded according to the severity of the lesion. The lesions developed much faster and were more severe in the left eyes. These results suggest that the body's immune mechanism participates in the pathogenesis of alkali corneal burns and adversely affects the development of this condition.