The present disclosure relates to compositions and methods for treating APOC3-related diseases such as: hypertriglyceridemia (e.g., Type V Hypertriglyceridemia), abnormal lipid metabolism, abnormal cholesterol metabolism, atherosclerosis, hyperlipidemia, diabetes, including Type 2 diabetes, obesity, cardiovascular disease, and coronary artery disease, among other disorders relating to abnormal metabolism or otherwise, using a therapeutically effective amount of a RNAi agent to APOC3.