Five hundred thirty-six cases of early breast cancer (T0 to T2, N0 to N1) treated with breast conservation therapy were monitored for a median interval of 64 months. Fifty-five locoregional failures occurred after a median interval of 40 months; the actuarial failure rate was 9% at 5 years and 19% at 10 years. Factors predicting locoregional failure were sought. Young patients had a higher risk of failure than older patients, although their actuarial survival rates were not different. Locoregional failure was defined as advanced if tumor involved skin or was fixed to the chest wall, the diameter was greater than 5 cm, or unresectable nodes were present. There was a significantly higher incidence of advanced recurrence with higher initial tumor stage. Overall, the 5-year survival rate after treatment of locoregional recurrence was 63%. Advanced locoregional failure, however, resulted in a median survival time of 37 months. Further study is required to explain the increased failure rate in younger women. Advanced locoregional failure rarely occurred after treatment of Stage 0 or Stage I tumors, supporting the selection of patients with early disease for breast conservation therapy.