BACKGROUND: The role of the renin-angiotensin-aldosterone system in COVID-19 is controversially discussed. SARS-CoV-2 enters host cells by binding to angiotensin-converting enzyme 2 and activity of the renin-angiotensin-aldosterone system may affect susceptibility to SARS-CoV-2 infection and outcome of patients with COVID-19. METHODS: In this prospective single-center study, we determined the serum levels of ACE-2, angiotensin II and aldosterone in patients with COVID-19 compared to control patients presenting with similar symptoms in the emergency unit. RESULTS: We analyzed serum samples from 24 SARS-CoV-2 positive and 61 SARS-CoV-2 negative patients. SARS-CoV-2 positive and control patients did not differ in baseline patients characteristics, symptoms and clinical presentation. Mean serum concentrations of ACE2, angiotensin II, and aldosterone did not differ between the SARS-CoV-2 positive and the control group. In line with this, serum potassium as surrogate parameter for RAAS activity and blood pressure were similar in both groups. CONCLUSIONS: In summary, we did not find evidence for altered RAAS activity including angiotensin II, aldosterone, or potassium levels, and blood pressure in patients with COVID-19.