Two cats with a superficial oral squamous cell carcinoma responded favorably to treatment using a 90Sr probe. From one to six fields were applied per tumor, depending on tumor size. The surface dose per treatment ranged from 75 to 150 Gy and the total surface dose ranged from 200 to 500 Gy. Adverse effects were minimal. The cats survived 7 months and 5 years 9 months from the time of diagnosis. These data indicate that with careful patient selection 90Sr may be useful for the treatment of feline oral squamous cell carcinoma in some patients.