Background: Early observational studies suggested that the use of the renin angiotensin system (RAS) inhibitors, specifically angiotensin converting enzyme inhibitors or angiotensin receptor blockers, may increase the risk of infection with SARS-CoV-2 and adversely affect the prognosis or survival of infected patients. To explore the impact of RAS inhibitor use on the risk of SARS-CoV-2 infection and the prognosis of SARS-CoV-2 infected patients, from all published studies. Methods and Findings: A systematic review and meta-analysis of the use of RAS inhibitors in relation to infection with SARS-CoV-2 and/or the severity and mortality associated with COVID-19 was conducted. English language bibliographic databases PubMed, Web of Science, OVID Embase, Scopus, MedRxiv, BioRxiv, searched from Jan 1st, 2020 to July 20th, 2020. 58 observational studies (69,200 COVID-19 patients and 3,103,335 controls) were included. There was no difference in the susceptibility to SARS-CoV-2 infection between RAS inhibitor users and non-users (unadjusted OR 1.05, 95% CI 0.90 to 1.21), (adjusted OR 0.93, 95% CI 0.85 to 1.02), (adjusted HR 1.07, 95% CI 0.87 to 1.31). There was no significant difference in the severe Covid-19 case rate between RAS inhibitor users and non-users (unadjusted OR 1.05, 95% CI 0.81 to 1.36), (adjusted OR 0.76, 95% CI 0.52 to 1.12), or in mortality due to COVID-19 between RAS inhibitor users and non-users (unadjusted OR 1.12, 95% CI 0.88 to 1.44), (adjusted OR 0.97, 95% CI 0.77 to 1.23), (adjusted HR 0.62, 95% CI 0.34 to 1.14). Conclusions: In the most comprehensive analysis of all available data to date, treatment with RAS inhibitors was not associated with increased risk of infection, severity of disease, or mortality due to COVID-19. The best available evidence suggests that these treatments should not be discontinued on the basis of concern about risk associated with COVID-19.