The invention relates to RNAi agents, e.g. double-stranded RNAi agents, targeting the HAO1 gene, and method of using such RNAi agents to inhibit expression of HAO1 and methods of treating subjects having, e.g., PH1. Described herein are double-stranded RNAi agents which inhibit the expression of a HA01 gene in a cell, such as a cell within a subject, e.g., a mammal, such as a human having a HAO1 associated disorder, and uses of such double-stranded RNAi agents. In certain aspects of the invention, substantially all of the nucleotides of an iRNA of the invention are modified.
