The present disclosure relates to methods of treating EPAS1-related diseases such as cancer, metastases, astrocytoma, bladder cancer, breast cancer, chondrosarcoma, colorectal carcinoma, gastric carcinoma, glioblastoma, head and neck squamous cell carcinoma, hepatocellular carcinoma, lung adenocarcinoma, neuroblastoma, non-small cell lung cancer, melanoma, multiple myeloma, ovarian cancer, rectal cancer, renal cancer, clear cell renal cell carcinoma (and metastases of this and other cancers), gingivitis, psoriasis, Kaposi's sarcoma-associated herpesvirus, preeclampsia, inflammation, chronic inflammation, neovascular diseases, and rheumatoid arthritis, using a therapeutically effective amount of a RNAi agent to EPAS1.