The prognostic implications of detection mode in local recurrence after lumpectomy and radiation therapy were assessed. Seventy-two women treated with lumpectomy and irradiation for American Joint Committee on Cancer stages I and II invasive breast cancer developed recurrent cancer in the ipsilateral breast, had physical examination and mammography performed at the time of recurrence, and underwent salvage mastectomy. There was a statistically significant association between detection with mammography alone and lower T stage (P = .05), and there was a nonstatistically significant trend toward noninvasive histologic findings. No significant association was noted between detection method and site of recurrent current cancer in the breast, interval to recurrence, or patient age. There were nonstatistically significant trends toward improved relapse-free survival and overall survival for patients with recurrences detected solely with mammography. that postirradiation surveillance mammography is important for the early detection of recurrent cancer. While the trend did not reach statistical significance, detection with mammography alone had a clinically apparent impact on relapse-free and overall survival.