Objective To test the hypothesis that there is a higher incidence of autoimmune disorders in patients who have undergone breast reconstruction with silicone gel implants rather than autogenous tissue. Design: Prospective study. Setting: Tertiary referral center dealing exclusively with cancer. Patients: All female breast cancer patients who underwent breast reconstruction between January 1986 and March 1992. Patients were nonrandomly assigned to breast reconstruction with one of the following four methods: (1) silicone gel implant only, (2) latissimus dorsi flap with implant, (3) latissimus dorsi flap without implant, and (4) transverse rectus abdominis flap. The first two groups made up the implant cohort and the last two groups the autogenous tissue cohort. Selection of reconstructive method was made on clinical grounds and was based on both physician and patient preference. Main outcome measures: Documented diagnosis of autoimmune disorder by Board‐certified rheumatologist. Results: Three hundred eight implants were used in 250 patients, and 408 reconstructions with tissue were performed on 353 patients. The two groups were similar in age and tumor stage. The two groups contributed 615.8 and 663.4 person‐years of follow‐up, respectively. One patient from each group (<0.5%) had a documented occurrence of an autoimmune syndrome requiring therapy. Both cases were considered mild, and after initial low‐dose steroid therapy, both patients are now off steroids. Conclusion: The incidence of autoimmune disease in mastectomy patients receiving silicone gel implants is not different than in patients who had reconstruction with autogenous tissue. Schusterman MA, Kroll SS, Reece GP, Miller MJ, Ainslie N, Halabi S, Balch CM. Incidence of autoimmune disease in patients after breast reconstruction with silicone gel implants versus autogenous tissue: a preliminary report. Ann Plast Surg 1993;31:1‐6