At the St. Francis Medical Center during the 20-year period 1960-1980, there were 1,148 primary breast cancers with a 7.1 percent incidence of synchronous and metachronous invasive primary breast cancer. Twenty-one cases (1.8 percent of the total series) illustrate noninvasive cancer of the breast. The essential approaches toward the diagnosis of a contralateral cancer were breast self-examination, history and physical examination, and x-ray mammography. Biopsy of contralateral discrete breast masses was advocated. If biopsies were positive for malignancy, definitive surgical management with indicated supplemental oncological therapy were recommended. "Blind focal biopsy" of the contralateral breast was discouraged. The five- to 25-year disease-free survival rate for 82 invasive bilateral breast cancers was 51 percent with a follow-up percentage of 98 percent during an interval of five to ten years. The survival statistics in the primary bilateral breast cancers when compared to results in primary unilateral breast cancers were not as grave as anticipated.