Current practice within the NHS Breast Screening Programme recommends surgical excision of screen detected areas of stromal deformity as differentiating carcinomas from radial scars and excluding in situ malignancy in association with radial scars is unreliable. We retrospectively reviewed all cases recalled for assessment over a 4 year period, identified to have an area of persistent stromal deformity not associated with surgical scarring and without an associated mammographic mass. Thirty women were prevalent (first) round screens--17 cases proved to be malignant and 13 benign. The latter group included three cases of atypical ductal hyperplasia. Nineteen women were incident (subsequent) round screens--all 19 cases proved to be malignant. This study supports the practice of surgically removing all areas of stromal deformity, particularly new areas of stromal deformity detected in the incident round, as in this group the likelihood of malignancy is extremely high.