To reduce the cosmetic deformity resulting from diagnostic biopsies, current breast screening guidelines recommend that 80% of biopsy specimens that subsequently prove to be benign should weigh less than 20 g. The relationship between specimen weight and cosmesis is unknown and evidence to support a 20 g upper limit is lacking. Patient satisfaction following all benign biopsies weighing more than 20 g (n = 49) and a random sample of 30 of those weighing less than 20 g (n = 103) performed by one screening unit, over a 6 year period, was assessed by a postal questionnaire. Overall, 32% of patients were unhappy with the cosmetic outcome of their surgery. Patient dissatisfaction appeared to increase with specimen weight (6/23 [26%] < 20 g versus 13/36 [36%] > 20 g) but no statistically significant relationship between weight and cosmesis was apparent (P = 0.57). Reducing benign breast biopsy specimen weights to a minimum is a desirable objective. However, the current quality standard is not evidence-based, is too stringent and should be revised. Strategies need to be introduced to improve patient satisfaction following breast wire-localisation biopsies. In particular, patients should be counselled pre-operatively regarding possible adverse cosmetic outcome.