AbstractObjectivesTo identify research priorities of people with Long COVID.DesignCitizen science study following an iterative process of patient needs identification, evaluation and prioritization. A Long COVID Citizen Science Board and a Long COVID Working Group were formed.SettingOnline participation with four activities: three remote meetings and one online survey. First, board members identified needs and research questions. Second, working group members and persons affected by Long COVID evaluated the research questions on a 1-5 Likert scale using an online survey. Then the board gave feedback on this evaluation. Finally, board members set the priorities for research through voting and discussion.Participants28 Long COVID Citizen Science Board members: 21 with Long COVID, and 7 with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). 30 Long COVID Working Group members: 25 with Long COVID, 4 ME/CFS patients, and 1 relative. 241 online survey respondents: 85.5% with Long COVID, 14.5% ME/CFS patients, and 7.1% relatives.Main outcome measuresPrioritization of Long COVID-related research questions.Results68 research questions were generated by the board and categorized into four research domains (medicine, health care services, socio-economics, and burden of disease) and 14 subcategories. Their average importance ratings were moderate to high and varied from 3.41 (SD = 1.16) for sex-specific diagnostics to 4.86 (SD = 0.41) for medical questions on treatment. Five topics were prioritised: “treatment, rehabilitation and chronic care management”, “availability of interfaces for treatment continuity”, “availability of healthcare structures”, “awareness and knowledge among professionals”, and “prevalence of Long COVID in children and adolescents”.ConclusionsTo our knowledge, this is the first study developing a citizen-driven, explicitly patient-centred research agenda with persons affected by Long COVID, setting it apart from existing multi-stakeholder efforts. The identified priorities could guide future research and funding allocation. Our methodology establishes a framework for citizen-driven research agendas, suitable for transfer to other diseases.What is already known on this topicLong-term health consequences following acute SARS-CoV-2 infection, referred to as post COVID-19 condition by WHO or as Long COVID by affected people, are increasing, with population-based prevalence estimates for adults at around 20%.Long COVID is associated with fatigue, shortness of breath, cognitive impairment, sleep disorders, pain and other health problems.There is little evidence about the needs of persons affected by Long COVID, and it is not clear which research questions should be prioritized to address these needs and help patients and their clinicians make informed and shared decisions about their care.What this study addsResearch priorities most important to persons affected by Long COVID are “treatment, rehabilitation and chronic care management”, “availability of interfaces for treatment continuity”, “availability of healthcare structures”, “awareness and knowledge among professionals”, and “prevalence of Long COVID in children and adolescents”.Our study may serve as model for a new framework for patient-centred citizen-driven research agendas and as guidance for funding bodies.