Background: Concerns have been raised on a potential interaction between renin-angiotensin system inhibitors (RASI) and the susceptibility to coronavirus disease 2019 (COVID-19). No data have been so far reported on the prognostic impact of RASI in patients suffering from ST-elevation myocardial infarction (STEMI) during COVID-19 pandemic, which was the aim of the present study. Methods: STEMI patients treated with primary percutaneous coronary intervention (PPCI) and enrolled in the ISACS-STEMI COVID-19 registry were included in the present sub-analysis and divided according to RASI therapy at admission. Results: Our population is represented by 6095 patients, of whom 3654 admitted in 2019 and 2441 in 2020. No difference in the prevalence of SARSCoV2 infection was observed according to RASI therapy at admission (2.5% vs 2.1%, p = 0.5), which was associated with a significantly lower mortality (adjusted OR [95% CI]=0.68 [0.51-0.90], P = 0.006), confirmed in the analysis restricted to 2020 (adjusted OR [95% CI]=0.5[0.33-0.74], P = 0.001). Among the 5388 patients in whom data on in-hospital medication were available, in-hospital RASI therapy was associated with a significantly lower mortality (2.1% vs 16.7%, OR [95% CI]=0.11 [0.084-0.14], p < 0.0001), confirmed after adjustment in both periods. Among the 62 SARSCoV-2 positive patients, RASI therapy, both at admission or in-hospital, showed no prognostic effect. Conclusions: This is the first study to investigate the impact of RASI therapy on the prognosis and SARSCoV2 infection of STEMI patients undergoing PPCI during the COVID-19 pandemic. Both pre-admission and in-hospital RASI were associated with lower mortality. Among SARSCoV2-positive patients, both chronic and in-hospital RASI therapy showed no impact on survival.