The current study examined predictors of mastectomy in a certified breast center with the main impact on the factor surgeon. A total of 663 patients were analyzed for their mastectomy rates. Included were patients with T1 and T2 tumors, who had their surgery performed by one of three specialized breast surgeons with a workload of at least 50 new breast cancer cases per year. On multivariate analysis central tumor localization, positive lymph node status, nonunifocality, large tumor size, and the surgeon were independent predictors of mastectomy. Surgeon A had a mastectomy rate of 30.5% (50/164), surgeon B 26.9% (43/160) respectively, and surgeon C had a mastectomy rate of 15.8% (27/171), p = 0.005. Patients, who had surgery performed by surgeon A or surgeon B were 2.34 [95% confidence interval (CI): 1.38-3.97, p < 0.005] respectively 1.96 (95% CI: 1.14-3.36, p = 0.01) times as likely to have a mastectomy than patients who had surgery performed by surgeon C. Even in a certified breast center with specialized breast surgeons the surgeon is an independent risk factor of mastectomy, as the tumor criteria are given at the time of diagnosis.