The invention relates to a double-stranded ribonucleic acid (dsRNA) for inhibiting the expression of a human PCSK9 gene in a cell, wherein said dsRNA comprises at least two sequences that are complementary to each other and wherein a sense strand comprises a first sequence and an antisense strand comprises a second sequence comprising a region of complementarity which is substantially complementary to at least a part of a mRNA encoding PCSK9, and wherein said region of complementarity is less than 30 nucleotides in length and wherein said dsRNA, upon contact with a cell expressing said PCSK9, inhibits expression of said PCSK9 gene, wherein (a) said first sequence is the sequence of SEQ ID NO: 1229 and said second sequence is the sequence of SEQ ID NO: 1230； (b) said first sequence is the sequence of SEQ ID NO: 1227 and said second sequence is the sequence of SEQ ID NO: 1228； or (c) said part of said mRNA encoding PCSK9 is the sequence from position 3530 to 3548 of the mRNA sequence of database entry NM_174936.
