Performance of periodic follow-up examinations after mastectomy for breast cancer is standard practice, primarily for early detection and treatment of recurrence. This study was designed to determine whether this routine screening resulted in significant survival benefit for the patient. The medical records of 1,230 women treated for cure of invasive carcinoma of the breast were reviewed, and 248 cases of recurrence were identified for analysis. Only 36% of recurrences were discovered asymptomatically. Asymptomatic recurrence was associated with favorable biologic factors, ie, more frequent estrogen receptor (ER) positivity and initial node negative status, and survival was superior to that of others. This was particularly true for occult local recurrence. However, compliance with a present schedule of examinations did not confer superior survival. It was concluded that (1) routine screening after mastectomy detects few recurrences that are not already symptomatic, and (2) the superior survival associated with discovery of occult recurrence may result from the influences of lead time and length bias.