Sixty Chinese breast cancer patients underwent ovarian irradiation with one of two dose schedules: 12 Gy/4 fractions/4-6 days or 14 Gy/4 fractions/4-6 days. The ovarian ablation failure rates were 14% and 0% respectively in patients above 40 years of age. The overall ablation failure rate in younger patients was unacceptably high at 35%. The significance of the findings is discussed.