Background. Breast cancer patients are recommended to have annual surveillance mammography (SM).Conclusion. This study supports the use of SM.Results. 32% had regular SM. 43 cases of CLBC were confirmed. Seventeen (40%) were detected by SM. Twenty-six (60%) were detected clinically. For detection of stage Tis/T1 by SM: OR 6.0; 95% CI 1.08--33.32, P = 0.07. For detection of stage N0 by SM: OR 7.2; 95% CI 1.35--38.3, P = 0.041. Use of SM was associated with a reduced risk of death: HR: 0.365 (95% CI 0.250--0.750).Methods. A case-cohort design was used to evaluate the outcomes of SM. The underlying population identified from administrative databases, included all women in the province of Ontario, Canada who had a total mastectomy for primary breast cancer between 1/7/1991 and 31/12/1993. A random sample of 800 was chosen for chart review to identify cases of CLBC.