The invention relates to an ofatumumab formulation comprising ofatumumab, 50mMsodium acetate, 51 mM chloride, 1% arginite free base, 0.05 mM EDTA and 0.02%polysorbate 80, with the formulation having a pH of 5.5. In addition toimproving stability,the formulation also prevents aggregation of the antibody.