Champigneulle, Benoit, Ivan Hancco, Richard Renan, Stéphane Doutreleau, Emeric Stauffer, Aurélien Pichon, Julien V. Brugniaux, Hélène Péré, Pierre Bouzat, David Veyer, and Samuel Verges. High-altitude environment and COVID-19: SARS-CoV-2 seropositivity in the highest city in the world. High Alt Med Biol. 22: 000-000, 2021. Background: A reduced coronavirus disease 2019 (COVID-19) diffusion has been suggested in high-altitude areas but remained questionable. Aims of this study were to estimate severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) seropositivity as well as the risk factors associated in La Rinconada, the highest city in the world (5,100-5,300 m), a gold-mining town located in southeastern Peru where >50,000 dwellers live in precarious sanitary conditions. Materials and Methods: We performed a cross-sectional study during a 1-week period in October 2020, using point-of-care lateral flow serological assays allowing detection of antibodies directed against SARS-CoV-2 among voluntary dwellers in La Rinconada. Participants were also questioned about potential occupational and environmental risk factors of COVID-19 occurrence. Results: In a sample of 159 dwellers tested in La Rinconada, 48.4% [95% confidence interval, CI: 40.5-56.4] were seropositive for the SARS-CoV-2. Occurrence of at least one symptom compatible with the COVID-19 over the past 6 months remained the only significant factor associated with SARS-CoV-2 seropositivity (adjusted odds ratio: 3.27; [95% CI: 1.70-6.44]; p < 0.001). Conclusions: The high rate of SARS-CoV-2 seropositivity observed in this small sample of highlanders does not support a protective effect of high-altitude against the COVID-19 spread and demonstrates its large dissemination in vulnerable populations. Clinical Trial Registration number: NCT04604249.