Introduction: Electronic patient-reported outcome (ePRO) systems have demonstrated to improve patient outcome in cancer, but have not yet been evaluated in patients with aplastic anemia (AA) and paroxysmal nocturnal hemoglobinuria (PNH). This pilot study evaluated the feasibility of an ePRO monitoring, self-management advice and warning system customized for AA and PNH patients.Methods: After adapting an ePRO system to the needs of AA and PNH patients (ePRO-AA-PNH), the application was tested by patients and their medical team for 6 months. Based on a predefined algorithm symptom reporting triggered self-management advice and prompts to contact clinicians in case of severe symptoms. Meanwhile the medical team could monitor ePROs in real-time and receive alerts of severe symptoms electronically. Results: Nine patients completed the study, showing a high adherence rate to the weekly symptom-reporting (72%), which decreased from 91 % to 53 % over the study period. Satisfaction was high: ePRO-AA-PNH was found easy to use, to understand and to integrate into daily life. Most patients (78%) would continue and all would recommend the application to other AA/PNH patients. Technical performance was rarely a barrier and healthcare providers saw ePRO-AA-PNH as a useful supplement, but missed the integration to clinical workflows and the hospital electronic health records (EHR). Conclusion: An ePRO system customized for AA and PNH was feasible to patients and their medical team in terms of adherence, satisfaction and performance, showing a high potential for these rare and chronic conditions. However, the integration into clinical workflows and hospital EHR is crucial for routine use.Trial registration: ClinicalTrials.gov identifier: NCT04128943, October 16 2019, https://clinicaltrials.gov/ct2/show/NCT04128943