Introduction The number of out-of-hospital cardiac arrest (OHCA) survivors is increasing. However, there remains limited knowledge on the long-term physical and psychological problems suffered by survivors and their relatives. The aims of the DANCAS (DANish cardiac arrest survivorship) survey are to describe the prevalence of physical and psychological problems, identify predictors associated with suffering them and to determine unmet rehabilitation needs in order to make recommendations on the timing and content of future rehabilitation interventions. Methods and analysis The DANCAS survey has a cross-sectional design involving a survey of OHCA survivors and their relatives. OHCA survivors will be identified through the Danish Cardiac Arrest Registry as having suffered an OHCA between 1 January 2016 and 31 December 2019. Each survivor will be asked to identify their closest relative to complete the relatives' survey. Contents of survivor survey: EQ-5D-5Level, Hospital Anxiety and Depression Scale, Two Simple Questions, Modified Fatigue Impact Scale, 12-item WHO Disability Assessment Scale 2.0, plus questions on unmet rehabilitation and information needs. Contents of relatives' survey: World Health Organisation-Five Well-Being Index, Hospital Anxiety and Depression Scale, Informant Questionnaire on Cognitive Decline in the Elderly - Cardiac Arrest and the Modified Caregiver Strain Index. Self-report outcome data collected through the surveys will be enriched by data from Danish national registries including demographic characteristics, circumstances of cardiac arrest and comorbidities. The survey will be completed either electronically or by post December 2020-February 2021. Ethics and dissemination The study will be conducted in accordance with the Declaration of Helsinki. Surveys and registry-based research studies do not normally require ethical approval in Denmark. This has been confirmed for this study by the Region of Southern Denmark ethics committee (20192000-19). Results of the study will be disseminated via several peer-reviewed publications and will be presented at national and international conferences.