OBJECTIVE: This study summarizes and compares clinical and laboratory characteristics of 34 patients admitted to the intensive care unit (ICU) for complications from coronavirus disease 2019 (COVID-19) at the First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China from Jan. 22 to Mar. 5, 2020. METHODS: A total of 34 patients were divided into two groups, including those who required noninvasive ventilation (NIV) and invasive mechanical ventilation (IMV) with additional extracorporeal membrane oxygenation (ECMO) in 11 patients. Clinical features of COVID-19 patients were described and the parameters of clinical characteristics between the two groups were compared. RESULTS: The rates of the acute cardiac and kidney complications were higher in IMV cases than those in NIV cases. Most patients had lymphocytopenia on admission, with lymphocyte levels dropping progressively on the following days, and the more severe lymphopenia developed in the IMV group. In both groups, T lymphocyte counts were below typical lower limit norms compared to B lymphocytes. On admission, both groups had higher than expected amounts of plasma interleukin-6 (IL-6), which over time declined more in NIV patients. The prothrombin time was increased and the levels of platelet, hemoglobin, blood urea nitrogen (BUN), D-dimer, lactate dehydrogenase (LDH), and IL-6 were higher in IMV cases compared with NIV cases during hospitalization. CONCLUSIONS: Data showed that the rates of complications, dynamics of lymphocytopenia, and changes in levels of platelet, hemoglobin, BUN, D-dimer, LDH and IL-6, and prothrombin time in these ICU patients were significantly different between IMV and NIV cases.