We aimed to retrospectively analyze the clinical and computed tomography (CT) characteristics of young adults with Coronavirus Disease 2019 (COVID-19) pneumonia who were critically ill and to identify the features associated with non-survival. Thirty-eight COVID-19 patients (20-45 years old, 28 men) who had been admitted in the intensive care unit were included, including 18 non-survivors (group 1) and 20 survivors (group 2). Their clinical characteristics and initial and follow-up CT were compared between groups. In group 1, the days from illness onset to death were 21.1 +/- 10.3 days; 7 patients had underlying comorbidities. At admission, group 1 exhibited higher serum ferritin and interleukin-6 (IL-6) levels (1142.6 +/- 242.4 mg/L and 33.8 +/- 18.6 mmol/L) compared with group 2 (728.3 +/- 150.9 mg/L and 15.2 +/- 6.9 mmol/L, P < .01). Group 1 exhibited more rapidly progressive opacities and consolidation in follow-up CT (16.7 +/- 3.1 scores, 15.7 +/- 3.1 segments) than group 2 (11.4 +/- 4.0 scores, 10.3 +/- 4.6 segments, P < .01). The oxygenation index was lower (87.6 +/- 19.2 vs 99.1 +/- 20.4 mm Hg) and the mechanical ventilation duration was longer (14.7 +/- 6.9 vs 9.7 +/- 3.7 days) in group 1 compare with group 2 (P < .01). Compared with the survivors, the non-survivors showed higher serum ferritin and IL-6 levels, more rapidly progressive opacities in CT, lower oxygenation index, and longer mechanical ventilation durations. Special attention to ferritin/IL-6 levels and oxygenation index as well as early CT application and timely reexaminations are important to identify the individuals who may be at risk of becoming critically ill.