Introduction Patients with obstructive lung diseases are possibly at risk of developing severe outcomes of coronavirus disease 2019 (COVID-19). Therefore, the aim of this study was to determine the risk of severe outcomes of COVID-19 among patients with asthma and COPD. Methods We performed a nationwide cohort study of patients with COVID-19 from 1 February to 10 July 2020. All patients with COVID-19 registered in the Danish registers were included. Using International Classification of Diseases (ICD) codes and medication history, patients were divided into asthma, COPD or no asthma or COPD. Primary outcome was a combined outcome of severe COVID-19, intensive care or death.