Introduction: The number of breast reconstructions after breast cancer is increasing over the years. This study evaluates complications in the first 30 days after breast reconstruction post mastectomy in different surgical techniques for patients with non-metastatic breast cancer. Methods: Retrospective cohort including patients who underwent breast reconstruction post mastectomy at the National Institute of Neoplastic Diseases (INEN) 2014-2018. Outcomes were immediate complications (first 30 days after surgery). Cumulative incidences were obtained. Association with clinical and demographic factors was evaluated using adjusted relative risk (aRR) obtained via Poisson Regression with robust variances. Results: 2092 patients had mastectomy at INEN during the study period, but only 271 underwent breast reconstruction. From them, 148 had complete data and fulfilled the selection criteria. Me...