Between 1962 and 1984, a total of 433 patients were treated at Yale-New Haven Hospital with conservative surgery and radiation therapy (CS + RT) to the intact breast. As of January 1990, with a minimum assessable follow-up of 5 years and a median follow-up of 8.21 years, there have been a total of 50 breast recurrences resulting in a 5-year actuarial breast recurrence rate of 8%. Of all clinical factors tested, young age was the most significant prognostic factor for local recurrence (P less than .03). In addition, patients with pathologically involved lymph nodes were noted to have a lower local recurrence rate than patients with pathologically negative axillae (P less than .05). These findings were especially notable given the fact that the node-positive group had a higher percentage of T2 tumors and a higher percentage of patients in the young age group. These paradoxical findings, however, may be explained by the fact that 88% of the node-positive patients underwent adjuvant systemic therapy in the form of either systemic chemotherapy or hormonal therapy, while only 8% of node-negative patients underwent any adjuvant systemic therapy. When analyzed as a function of adjuvant therapy, those patients receiving adjuvant therapy had a lower local recurrence rate than those patients not receiving adjuvant therapy (P less than .08). We conclude that adjuvant systemic therapy impacts on the ipsilateral breast recurrence rate in patients treated with CS + RT. The implications of this study in light of the widespread use of adjuvant systemic therapy are discussed.