With digital patient-reported outcome (PRO) tools in clinical practice, patients are given new tasks of providing data that aim at supporting and individualising care, simultaneously reducing unnecessary clinical visits. While the innovative potential of mobilising PRO data for care is increasingly explored, little attention is given to the efforts that the provision of PRO data rests on – that of the patients. Based on ethnographic fieldwork carried out among cancer patients receiving PRO-based follow-up care, we argue that with the increased reliance on patient-generated health data, we need to consider patients’ data work. Drawing on emerging literature on healthcare professionals’ data work and the rich work in sociology and Science and Technology Studies (STS) on patients’ active engagement in shaping and managing care, we conceptualise PRO patient data work as two simultaneous processes: the process of data filtering – patients filter information to fit the envisaged recipient and purpose; and the process of data sensing – patients evaluate their embodied experiences. By doing so, we show that patients’ data work has implications beyond simply providing data that represent their experiences.