The intensity of deep-sea fisheries on the high seas and the impacts on the marine environment call for effective measures to ensure that fishing does not compromise the commitments established for protecting biodiversity in the deep ocean by the United Nations. In order to prevent significant adverse impacts (SAIs) on vulnerable marine ecosystems (VMEs), high seas fishing nations agreed to stop fishing activities where VMEs are known or likely to occur unless the fishing can be managed to prevent SAIs on VMEs. To determine whether fishing activities can be conducted in a sustainable manner that prevents impacts on VMEs, States agreed on criteria for conducting impact assessments (IAs) for deep-sea fisheries through a set of Guidelines negotiated under the auspices of the United Nations Food and Agriculture Organisation (FAO Guidelines). The FAO Guidelines were adopted in 2009 (FAO 2009) and later that year the UN General Assembly (UNGA) expressly committed States to ensuring that bottom fishing is prohibited unless prior impact assessments consistent with the FAO Guidelines have been carried out. Despite progress made by States and Regional Fisheries Management Organisations and Agreements (RFMO/As) to conduct IAs, there remain significant gaps in the implementation of the IAs following the FAO criteria and commitments in the UNGA resolutions. This report describes the results of a review of a selection of IAs for deep-sea fishing on the high seas conducted by members of the Fisheries Working Group of the Deep-Ocean Stewardship Initiative (DOSI), consisting of a multidisciplinary group of deep-sea ecology, fisheries and policy experts. The nine selected IAs have either been submitted by States to RFMO/As, have been conducted by the RFMO/A itself, or represent an independent evaluation prepared by a fishing nation. The overall goal of the review was to evaluate the content and consistency of the selected IAs against the science-based criteria established in the FAO Guidelines in light of the UNGA resolutions committing States to conduct the assessments consistent with the Guidelines.