In this preprint study of the RECOVERY clinical trial involving 6,425 hospitalized patients with COVID-19, Horby et al. report that patients receiving a 6 mg daily dose of the corticosteroid dexamethasone had a reduced 28-day mortality compared with those receiving standard of care. Importantly, dexamethasone reduced death by one-third in patients receiving invasive mechanical ventilation and by one-fifth in patients requiring oxygen only but showed no benefit in patients who did not require respiratory support. Overall, the results of this study suggest that dexamethasone, an inexpensive and widely available anti-inflammatory drug, is a valuable treatment for severe cases of COVID-19.