['To compare the frequency of residual tumour in the cavity wall in patients with positive resection margins undergoing either immediate re-excision (IR) at the time of surgery or delayed re-excision (DR) to investigate the effects of recent surgery on the detection of residual disease.', 'Records of 125 patients who had undergone wide local excision with positive margins were examined. In 64 patients re-excision was performed immediately and in 61 it was delayed by 13-69 days. The presence or absence of residual disease in the re-excision specimens was recorded.', 'Residual tumour was detected in 40/64 (62%) and 20/61 (33%) DR specimens (P<0.001). DR specimens contained areas of fibrosis, fat necrosis and foreign body giant cell changes.'] Does the timing of surgery affect the detection of residual disease after wide local excision of breast carcinoma?