Background. Tocilizumab, a drug targeting interleukin-6 administrated in the right timeframe may be beneficial in coronavirus-disease-2019 (COVID-19). We aimed to assess its benefit, drawing from observations in compassionately treated patients. Methods: In a retrospective case-control study, treatment effect (tocilizumab 400mg, single-dose) was assessed using three statistical methods: propensity-score matching, Cox multivariable survival and inverse probability score weighting (IPSW) analyses. Were included all patients hospitalized with COVID-19, who presented severity criteria with SpO2<96% despite O2-support >6L/min for more than 6 hours. Were excluded patients in critical care medicine department and those under invasive mechanical ventilation. Primary outcome was a composite of mortality and ventilation, with a maximum follow-up of 28 days. Results: 246 patients were included (106 treated by tocilizumab). They were 67.6 +/-15.3 years-old, with 95 (38.5%) women. Delay between first symptoms and inclusion was 8.4 +/-4.5 days. Overall, 105 (42.7%) patients presented the primary outcome, with 71 (28.9%) deaths during the 28-days follow-up. Propensity-score-matched 84 pairs of comparable patients. In the matched cohort (n=168), tocilizumab was associated with fewer primary outcomes (hazard ratio (HR)=0.49 (95% confidence interval (95CI)=0.3-0.81), p-value=0.005). These results were similar in the overall cohort (n=246), with Cox multivariable analysis yielding a protective association between tocilizumab and primary outcome (adjusted HR=0.26 (95CI=0.135-0.51, p=0.0001), confirmed by IPSW analysis (p<0.0001). Analyses on mortality with 28-days follow-up yielded similar results. Conclusion: In this retrospective study, tocilizumab single-dose was associated with improved survival without mechanical ventilation in patients with severe COVID-19.