BACKGROUND Patients with coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 can rapidly progress to acute respiratory distress syndrome (ARDS). Because clinical diagnosis of ARDS includes several diseases, understanding the characteristics of COVID-19-related ARDS is necessary for precise treatment. We report 2 patients with ARDS due to COVID-19-associated pneumonia. CASE REPORT Case 1 involved a 72-year-old Japanese man who presented with respiratory distress and fever. Computed tomography (CT) revealed subpleural ground-glass opacities (GGOs) and consolidation. Six days after symptom onset, reverse transcription-polymerase chain reaction (RT-PCR) testing confirmed the diagnosis of COVID-19-associated pneumonia. He was intubated and received veno-venous extracorporeal membrane oxygenation (ECMO) 8 days after symptom onset. Follow-up CT revealed large diffuse areas with a crazy-paving pattern and consolidation, which indicated progression of COVID-19-associated pneumonia. Following treatment with antiviral medications and supportive measures, the patient was weaned off ECMO after 20 days. Case 2 involved a 70-year-old Asian man residing in Canada who presented with cough, malaise, nausea, vomiting, and fever. COVID-19-associated pneumonia was diagnosed based on a positive result from RT-PCR testing. The patient was then transferred to the intensive care unit and intubated 8 days after symptom onset. Follow-up CT showed that while the initial subpleural GGOs had improved, diffuse GGOs appeared, similar to those observed upon diffuse alveolar damage. He was administered systemic steroid therapy for ARDS and extubated after 6 days. CONCLUSIONS Because the pattern of symptom exacerbation in COVID-19-associated pneumonia cases seems inconsistent, individual treatment management, especially the CT-based treatment strategy, is crucial.