Between 1975 and 1980, 392 patients with a palpable mass or masses were referred for breast evaluation, including risk factor assessment, physical examination, and selective utilization of aspiration cytology and mammography. Three-hundred and thirty-one (85%) were biopsied, with a benign diagnosis in 65% of the patients and cancer in 35%. The 61 patients (15%) who were not biopsied consisted of 32 patients in whom the mass disappeared on follow-up examination, 20 with stabilization on long-term follow-up, and nine with decreased mass size. Most breast masses must be biopsied, but a few can be followed and biopsy avoided. However, a decision not to biopsy requires more precise clinical judgement and experience than a decision to proceed with biopsy. Absolute indications for breast biopsy include a clinically suspicious mass, a mammogram considered malignant or suspicious, aspiration cytologic findings reported as malignant or suspicious, and a persisting, dominant mass, even if clinically benign.