Elastosis, the presence of clumps of elastic fibers, is known to occur frequently in association with breast carcinoma. To test the hypothesis that the degree of elastosis increases progressively in fibrocystic disease with the severity of epitheliosis (epithelial hyperplasia, papillomatosis; widely believed to be the only premalignant component of fibrocystic disease) and increases further with intraductal and infiltrating duct carcinoma, breast tissue stained for elastic fibers from 84 women in the fifth decade of life was studied. Fourteen cases were evaluated in each of six disease categories: fibrocystic disease without epitheliosis; fibrocystic disease with epitheliosis, graded subjectively as mild, moderate, or severe (based on the degree of epithelial hyperplasia); intraductal carcinoma; and infiltrating duct carcinoma of the breast. Periductal elastosis and stromal elastosis were graded on a scale of 0 to 4 (absent to massive). The grades of both periductal elastosis and stromal elastosis were compared with those for the six disease categories ranked by increasingly advanced disease. The results indicate that the grades of periductal elastosis (Spearman rank correlation coefficient [R] = 0.54; P less than 0.001) and stromal elastosis (R = 0.75; P less than 0.001) increase progressively with the severity of breast disease.