THE MAJORITY of reports on radiation therapy of the eyes are concerned with gamma rays. The purpose of this paper, however, is to discuss the use of the less well known beta rays in the treatment of nonmalignant lesions of the lids and the anterior ocular segment. Beta rays possess the same qualities as other rays in the power of selective tissue destruction, but, in contrast to gamma rays, they penetrate about 3 mm. of tissue only. This makes them ideally suited to treatment of the anterior ocular segment. In no single case in which this therapy has been used has any damage to the lens been observed. This has been true clinically, as well as in animal experiments, in which in 1 instance a rabbit cornea was given 300 gram seconds of beta rays without a resultant cataract.1 The ease of application is a great advantage in the