Objective: Both 2019 novel coronavirus disease (COVID-19) and avian influenza A (H1N1) are serious acute respiratory diseases with a predisposition to acute respiratory distress syndrome (ARDS). Our aim was to compare the clinical characteristics of patients with COVID-19 and H1N1 influenza complicated with ARDS.Methods: We retrospectively studied data of 12 patients with ARDS (7 with COVID-19; 5 with H1N1 influenza) who were managed at The Second Affiliated Hospital of Xiamen Medical College and Xinglin Branch of the First Affiliated Hospital of Xiamen University between December 20, 2019 and February 29, 2020. We extracted the clinical information and outcomes from the hospital medical charts.Results: Patients with COVID-19 were older and were more likely to have underlying diseases. Low-to-moderate fever was more frequent and upper respiratory tract symptoms were less common in COVID-19 patients. Chest computed tomography of patients with COVID-19 more frequently revealed bilateral nodular patchy ground-glass opacities in the subpleural and central lobular regions. Heart disorders and pleural effusion were less frequent, and coagulopathy was more common in patients with COVID-19. The average duration of stay in the respiratory intensive care unit was longer in patients with COVID-19. The disease severity and clinical outcomes did not differ significantly between the two groups.Conclusion: Older age, higher comorbidity frequency, abnormal coagulation responses, longer hypoxemia duration, pulmonary fibrosis, and poorer clinical outcomes are the main characteristics in patients with COVID-19 who have ARDS. This calls for closer dynamic monitoring and more rigorous follow-up.