Four patients with carcinoma in situ were treated with strontium-90 beta ray application. The dose used was 4,500 rads after surgical removal or with small recurrent tumor and 7,000 rads for primary treatment. All patients were disease-free at follow-up periods of 48 to 320 months after treatment. One patient required superficial x-ray treatment for recurrent disease. No serious complications developed with the treatment and no progressive cataracts have occurred.