Reduction mammaplasty is commonly performed for bilateral macromastia, congenital asymmetry, or as a contralateral symmetry procedure in breast reconstruction following mastectomy for cancer. Occult carcinoma has been detected in 0.06 percent to 0.4 percent of breast reduction specimens. The purpose of this study was to examine the incidence of breast cancer in breast reductions performed in one institution over a 14-year period. The authors reviewed their experience with 800 reduction mammaplasties performed between 1988 and 2001. Six cancers were detected (0.8 percent). Of these cancers, three were invasive (0.4 percent) and three were ductal carcinoma in situ (0.4 percent). Stratified by indication for surgery, there was a trend toward higher detection rates in the reconstruction group (1.2 percent) compared with the macromastia (0.7 percent) or congenital asymmetry (0 percent) groups. Mammography was performed preoperatively in these patients and all results were negative for masses or suspicious microcalcification. Pathological diagnosis was guided by gross specimen evaluation in two patients and specimen radiography in one patient. Reduction mammaplasty has a small but definite risk of finding cancer in the resection specimen.