Tocilizumab (TCZ), a monoclonal antibody against interleukin-6 (IL-6), emerged as an alternative treatment for COVID-19 patients with a risk of cytokine storms recently. In the present study, we aimed to discuss the treatment response of TCZ therapy in COVID-19 infected patients.The demographic, treatment, laboratory parameters of C-reactive protein (CRP) and IL-6 before and after TCZ therapy, and clinical outcome in the 15 COVID-19 patients were retrospectively assessed.Totally 15 patients with COVID-19 were included in this study. 2 of them were moderately ill, 6 were seriously ill and 7 were critically ill. The TCZ was used in combination with methylprednisolone (MP) in 8 patients. 5 patients received the TCZ administration twice or more. Although TCZ treatment ameliorated the increased CRP in all patients rapidly, for the 4 critically ill patients who received only single dose of TCZ, 3 of them (No. 1, 2, and 3) still dead and the CRP level in the rest 1 patient (No. 7) failed to return to normal range with a clinical outcome of disease aggravation. Serum IL-6 level tended to further spiked firstly and then decreased after TCZ therapy in 10 patients. A persistent and dramatic increase of IL-6 was observed in these 4 patients who failed treatment.TCZ appears to be an effective treatment option in COVID-19 patients with a risk of cytokine storms. And for these critically ill patients with elevated IL-6, repeated dose of the TCZ is recommended. This article is protected by copyright. All rights reserved.