[en] A 51-year-old male with basal carcinoma of the left upper eye lid received surgical resection and 4 MeV electron beam therapy with a total dose of 3200 rad. In spite of the lead plate protection of cornea from the beam, corneal ulcer developed one year later. The cause of the ulcer seemed to be due to the edge effect of the beam in addition to increased sensitivity to the beam induced by mechanical injuries by the plate. We concluded that the correct usage of lead plate was important for prevention of corneal damage in the electron beam therapy. (author)