The appearance of metastatic disease decades after primary treatment for cancers occurs rarely with cancers of the breast, malignant melanoma, and cancers of the kidney. Certainty about the relationship of primary and metastatic cancers is often limited by the absence of tissues showing identical histology, omission of various procedures and tests ruling out a new primary cancer, and follow-up data with treatment which supports the case for late recurrence. We report here the unusual case of an 84-year-old woman initially treated with mastectomies for a benign breast condition at age 39 and invasive breast adenocarcinoma at age 44. A pleural effusion developed at age 83 which showed adenocarcinoma. Physical examination and an extensive evaluation were unrevealing. Hormonal treatment has sustained remission of disease for 1 year.