The Trans-Pacific Partnership (TPP) Agreement is a proposed free trade agreement between the US and 11 other countries in Asia and South America covering many consumer goods, including prescription medicines. This review describes how the TPP could affect international laws governing intellectual property rights for prescription drugs, focusing on patents and exclusivity protections for test data, including their effect on reimbursement decisions by national health care authorities responsible for health priority setting. We conclude that the TPP could affect low-income patients' access to medicines in signatory countries.