Twelve women who developed breast cancer at the site of old surgical scars in the breast are presented. Six had had former breast biopsies, 3 drainage of breast abscesses, and 3 developed breast cancer in old thoracotomy scars transversing the breast. The combination of trauma as an oncogen and scar tissue as a functional and immunological locus minoris resistentia seems to play a major role in the development of breast cancer in this group of patients. The associaton of breast cancer, scar, and trauma would not be coincidental. Increased attention drawn to this entity may lead to a rise in the number of cases diagnosed among patients with breast scars after biopsies, abscesses, trauma, or foreign body implantation.