Provided are methods and compositions for inhibiting MASP-3-dependent complement activation in a subject suffering from paroxysmal nocturnal hemoglobinuria by administering to the subject a composition comprising an amount of a MASP-3 inhibitory agent in an amount effective to inhibit MAS P-3-depencien! complement activation. Also provided are methods and compositions for increasing the survival of red blood cells in a subject suffering from paroxysmal nocturnal hemoglobinuria by administering to the subject a composition comprising an amount of at least one of a MASP-1 inhibitory agent and/or a MAS P-3 inhibitory agent effective to increase the survival of red blood cells. The subject may be administered a MASP-2 inhibitory agent and a MASP-1 inhibitory agent, a MASP-2 inhibitory agent and a MASP-3 inhibitory agent, administered, a MASP-3 inhibitory agent and a MASP-1 inhibitory agent, or a MASP-1 inhibitory agent, a MASP-2 inhibitory agent and a MASP-3 inhibitory agent.
