Background: Core outcome sets (COS) are being developed in many clinical areas to increase the quality and comparability of clinical trial results as well as to ensure their relevance for patients. A COS represents an agreed standardized set of outcomes that describes the minimum that should be consistently reported in all clinical trials of a defined area. It comprises a core domain set (defining what core outcomes should be measured) and a core measurement set (defining measurement/assessment instruments for each core domain). For pressure ulcer prevention trials a COS is lacking. The great heterogeneity of reported outcomes in this field indicates the need for a COS. Methods/design: The first part of this project aims to develop a core domain set by following established methods, which incorporates four steps: (1) definition of the scope, (2) conducting a scoping review, (3) organizing facilitated workshops with service users, (4) performing Delphi surveys and establishing consensus in a face-to-face meeting with different stakeholders. Discussion: After achieving consensus on the core domain set, further work will be undertaken to determine a corresponding core measurement set. This will lead to better pressure ulcer prevention research in the future. There are a number of methodological challenges in the field of COS development. To meet these challenges and to ensure a high-quality COS, the OUTPUTS project affiliates to current standards and works in close collaboration with international experts and with existing international service user groups.