Fifteen patients with malignant epithelial tumors of the conjunctiva were treated with beta-ray ocular applicators filled with radioactive strontium and yttrium (90Sr/90Y). Histologic examination confirmed the diagnosis. There were ten squamous cell carcinomas, four carcinomas in situ, and one case of epidermidalization. In one patient, who may have received an insufficient dose, recurrence led to enucleation. Radiogenic complications-secondary glaucoma and corneal degeneration-caused visual loss in two other patients. All of the other tumors disappeared completely without seriously affecting the eyes. Beta-ray irradiation with 90Sr/90Y applicators was effective if a sufficient dose (15,000 to 18,000 rads) was applied to the tumor surface and if the height of the tumor did not exceed 5 mm.