BACKGROUND. Controversy exists concerning the roles of mammography and physical examination in the detection of local recurrence after conservation therapy for breast carcinoma. In addition, the prognostic factors for and optimal treatment of patients with local recurrence are uncertain. METHODS. At eight radiotherapy institutes, two cancer institutes, and one surgical clinic in the Netherlands, regular follow-up of patients who underwent breast conservation therapy between 1980 and 1992 identified 266 patients with local recurrence in the breast. These patients exhibited no clinical signs of distant metastases at the time of diagnosis of the local recurrence. Data on the method of detection were available for 189 patients (72%). Local recurrence was diagnosed by mammography alone in 47 cases (25%). Of all patients, 85% underwent salvage mastectomy, 8% underwent local excision, 4% received systemic treatment only, and 3% remained untreated. Specimens of the primary tumor were available for review from 238 of the 266 patients (89%). RESULTS. Local recurrences detected by mammography alone were smaller than those detected by physical examination (P = 0.04). At 5 years from the date of salvage treatment, the overall survival rate for all 266 patients was 61% (95% confidence interval [CI], 55-67%), and the distant recurrence free survival rate was 47% (95% CI, 40-53%). For the 25 patients with noninvasive recurrence, these figures were 95% and 94%, respectively. Skin involvement, the extent of recurrence (≤10 mm vs. >10 mm), and both lymph node status and histologic grade of the primary disease were strong predictors for distant metastases in patients with invasive recurrence. CONCLUSIONS. Patients with invasive local recurrence more than 1 cm in size are at a substantial risk for distant disease. The better distant disease free survival for patients with recurrence measuring 1 cm or less may indicate that early detection can improve the treatment outcome. Recurrence with skin involvement should be considered generalized disease.