Background/Objectives: Rituximab is a standard of care therapy for patients with ANCA-associated vasculitis. When rituximab is contraindicated, or in the case of refractory disease, other treatments are needed. Obinutuzumab is another anti-CD20 antibody for the treatment of hematologic malignancies that may induce a deeper B-cell depletion compared to rituximab. Presented here is a series of three cases of patients with ANCA-associated vasculitis who were treated with obinutuzumab due to their history of anaphylactic reactions to rituximab. Methods: Case series of three patients with ANCA-associated vasculitis treated with obinutuzumab. Results: One female patient with microscopic polyangiitis and two male patients with granulomatosis with polyangiitis received obinutuzumab. The treatment was well-tolerated in all patients despite previous anaphylactic reaction to rituximab. Obinutuzumab was effective in i) inducing disease remission, ii) causing total B-cell depletion, and iii) resulting in undetectable serum titers of ANCA. All three patients were retreated with obinutuzumab for maintenance of remission. Conclusions: Rituximab is the standard of care for treatment of ANCA-associated vasculitis. However, these three cases support the use of obinutuzumab as an alternative to rituximab for treatment of ANCA-associated vasculitis. Obinutuzumab offered the option of giving a chemically dissimilar CD20 depleting agent with the expectation that it would be as efficacious as rituximab for ANCA-associated vasculitis without the risk of an allergic response in these patients and without the need to try a desensitizing regimen for rituximab. Because obinutuzumab is considered to result in a more profound and longer-lasting depletion of total body B cell population, it is theoretically possible that use of this drug might provide better control of vasculitis than rituximab. Prospective studies comparing rituximab to obinutuzumab in ANCA-associated vasculitis patients are warranted. Disclosures: CL reports honoraria from Bristol Myers Squibb and research grants from Bristol Myers Squibb, GlaxoSmithKline, and Genentech. AG Consulting: Aurinia pharmaceuticals, GSK, ValenzaBio, Horizon Therapeutic and Alnylam, Educational grant funding: Kaneka Medical America and Aurinia Pharmaceuticals, Research Support Travere Therapeutics. PM reports Consulting: AbbVie, AstraZeneca, Boeringher-Ingelheim, Bristol-Myers Squibb, ChemoCentryx, CSL Behring, Dynacure, EMDSerono, Forbius, Genentech/Roche, Genzyme/Sanofi, GlaxoSmithKline, InflaRx, Jannsen, Kiniksa, Kyverna, Magenta, MiroBio, Neutrolis, Novartis, Pfizer, Sparrow, Takeda, Talaris. Research Support: AbbVie, AstraZeneca, Boeringher-Ingelheim, Bristol-Myers Squibb, ChemoCentryx, Eicos, Forbius, Genentech/Roche, Genzyme/Sanofi, GlaxoSmithKline, InflaRx, Sanofi, Takeda. Royalties: UpToDate.