Adjunctive therapy with polyclonal intravenous immunoglobins (IVIg) is currently used for preventing or managing infections and sepsis, especially in immunocompromised patients. The pathobiology of COVID19 and the mechanisms of action of Ig led to consider this adjunctive therapy also in patients with respiratory failure by SARS-CoV2 infection. This manuscript report the rationale, the available data and the results of a structured consensus on intravenous Ig therapy in patients with severe COVID19. METHODS A panel of multidisciplinary experts defined the clinical phenotypes of COVID19 patients with severe respiratory failure and, after literature review, voted for the agreement on the rationale and the potential role of IVIg therapy for each phenotype. Due to the scarce evidence available, a modified RAND/UCLA appropriateness method was used. RESULTS Three different phenotypes of COVID19 patients with severe respiratory failure were identified: patients with an abrupt and dysregulated hyperinflammatory response (early phase), patients with suspected immune-paralysis (late phase), and patients with sepsis by hospital-acquired superinfection (sepsis by bacterial superinfection). The rationale for intravenous Ig therapy in the early phase was considered uncertain whereas the panellists considered appropriate its use in the late phase and patients with sepsis/septic shock by bacterial superinfection. CONCLUSION As with other immunotherapies, IVIg adjunctive therapy may a potential role in the managing of COVID19 patients. The ongoing trials will clarify the appropriate target population and the true effectiveness.