Abstract: A stable aqueous composition comprising (a) about 10 to about 100 mg/ml of an anti-C5 antibody, (b) a surfactant, (c) a stabilizer, and (d) a buffer having a pH of about 5.0 to about 7.8, wherein the stabilizer is trehalose, sucrose, sorbitol, arginine, or a combination thereof is provided. In a particular embodiment, the stable aqueous composition consists essentially of (a) about 10 or about 50 mg/ml of an anti-C5 antibody, (b) about 0.01 to about 0.1% (w/v) of a surfactant, (c) about 1 to about 20 mM buffer having a pH of 5.5 to 7.5, and (d) a stabilizer selected from the group consisting of trehalose, sucrose, sorbitol, arginine, or a combination thereof. A method of treating a disorder in which C5 activity is detrimental in a subject comprising administering the stable aqueous composition to the subject also is provided.