Abstract: Introduction. Opinions of influence of the Excisional Biopsy (EB) and delayed mastectomy on survival at Breast Cancer (BC) remain inconsistent. Studying of influence of a time interval between EB and a mastectomy on ten-year the general (OS) and disease free (DFS) survival of patients with BC became the purpose of this research.The analysis of patients with BC (n = 698) at stages T2 N0-3 M0 is carried out.Group A-the patients who had a mastectomy on day of EB (n = 556). Group B - the patients who had the delayed mastectomy (n = 142). Ten-year OS and DFS survival is investigated (Kaplan-Meier, log-rank test). The status of regional lymph nodes (LNs) (N0 or N1-3) and the BC laterality were considered. At N0 the survival of Group A was significantly below, than survival of Group B (OS: p = 0.0081; DFS: p = 0.009). At N1-3 of difference of survival of the compared groups were not significant (OS: p = 0.69; DFS: p = 0.39). At the right-sided BC at N0 of distinction of survival of groups were not significant (OS: p = 0.17; DFS: p = 0.25). At the left-sided BC at N0 the survival of Group A was significantly below, than survival of Group B (OS: p = 0.024; DFS: p = 0.012). Influence of delayed mastectomy on survival can depend on LNs status and BC laterality.