The authors compared skin-sparing mastectomy and traditional mastectomy both followed by immediate reconstruction in the treatment of breast cancer. Skin-sparing mastectomy is used increasingly in the treatment of breast cancer to improve the aesthetic results of immediate reconstruction. The oncologic and reconstructive outcomes of this procedure have never been analyzed closely. Institutional experience with 435 consecutive patients who underwent total mastectomy and immediate reconstruction from January 1989 through December 1994 was examined. Mastectomies were stratified into skin-sparing (SSM) and non-skin-sparing (non-SSM) types. Three hundred twenty-seven SSMs and 188 non-SSMs were performed. The mean follow-up was 41.3 months (SSM, 37.5 months, non-SSM, 48.2 months). Local recurrences from invasive cancer occurred after 4.8% of SSMs versus 9.5% of non-SSMs. Sixty-five percent of patients who underwent SSMs had nothing performed on the opposite breast versus 45% in the group of patients who underwent non-SSM (p = 0.0002). Native skin flap necrosis occurred in 10.7% of patients who underwent SSMs versus 11.2% of patients who underwent non-SSMs. Skin-sparing mastectomy facilitates immediate breast reconstruction by reducing remedial surgery on the opposite breast. Native skin flap necrosis is not increased over that seen with non-SSM. Skin-sparing mastectomies can be used in the treatment of invasive cancer without compromising local control.