ABSTRACT Introduction: Surgical site infections are one of the main problems related to health care. In Brazil, they are responsible for 14 to 16% of infections related to health care. This study sought to analyze the effect of implementing a package of measures to reduce surgical site infections (SSI) in heart surgeries, kidney transplants and herniorrhaphies and to evaluate adherence to the safe surgery checklist in a university hospital. Methods: this is a retrospective cohort study with data collection in a time series for the period from 2018 to 2020. Results: we analyzed 222 medical records referring to the surgeries under study performed in the year 2020, in which data were collected from the patients and the care package prevention measures. SSI data and adherence to the safe surgery checklist were analyzed in the years 2018, 2019 and 2020, totaling 268, 300 and 222 procedures analyzed, respectively. Conclusion: the study showed a significant reduction in the SSI rate with greater adherence to the protocol, which was not maintained and was influenced by the COVID-19 pandemic. Thus, the sustainability of this action represents a challenge to be overcome, in order to establish a safer environment for the patient and a better quality of service.