The invention relates to iRNA, e.g., double-stranded ribonucleic acid (dsRNA), compositions targeting the complement factor B (CFB) gene, the complement component C3 gene, and the complement component C9 gene and methods of using such iRNA, e.g., dsRNA, compositions to inhibit expression of CFB, C9 and/or C3 and to treat subjects having a complement component-associated disease, e.g., paroxysmal nocturnal hemoglobinuria and atypical hemolytic uremic syndrome.