At Yale-New Haven Hospital conservative treatment of early stage breast carcinoma with lumpectomy and radiation therapy has been used with increasing frequency since the 1960s. We have reviewed our experience with specific reference to prognosis following local recurrence. Between January 1962 and December 1984 a total of 433 patients were treated with conservative surgery and radiation therapy using standard techniques. As of December 1989, with minimum evaluable follow-up of 5 years and a median follow-up of 8.21 years, there have been a total of 50 ipsilateral breast recurrences resulting in a 5-year actuarial breast recurrence rate of 8%. Extent of disease at the time of local recurrence was clinically categorized as localized (less than 3 cm without dermal involvement) or diffuse (greater than 3 cm and/or with dermal involvement). Seventy-two percent of the recurrences were at or near the original tumor site whereas 28% recurred elsewhere in the breast. At a median follow-up post recurrence of 5.0 years (range 0.3-16.9 years), the 5-year actuarial survival for breast recurrences was 59% and the 5-year disease-free survival was 65%. A number of clinical and pathological features at the time of original diagnosis as well as at the time of local recurrence were tested as possible prognostic indicators for survival following local recurrence. By univariate analysis, significant factors associated with survival following local recurrence included extent of local disease at the time of recurrence (p less than .01), time to local recurrence (p less than .03), with later recurrences doing better, and site of local recurrence (p less than .01), with recurrences elsewhere in the breast doing better. We conclude from this large single institutional experience with a median follow-up post-recurrence of over 5 years that patients experiencing a local recurrence in the conservatively treated breast have a relatively favorable prognosis. The prognostic factors correlating with survival and implications regarding adjuvant systemic therapy at the time of local recurrence are discussed.