Objectives Self-monitoring the disease course is a relatively new concept in the management of patients with inflammatory rheumatic diseases (IRDs). The aims of this pilot study were to obtain patients’ experiences with online self-monitoring, to assess information about the agreement between the disease course assessed with patient-reported outcome measures (PROMs) and an objectively measured Disease Activity Score 28 (DAS28) by the rheumatologist, and to assess adherence to predetermined PROM frequency intervals. Design Observational study using qualitative and quantitative methods. Setting The rheumatology outpatient clinic of a teaching hospital in The Netherlands (secondary care). Participants 47 patients with an IRD who regularly attended the outpatient clinic. Methods Patients completed PROMs by using an online self-monitoring program. Their experiences regarding self-monitoring were qualitatively assessed through a focus group discussion and telephone interviews using a thematic analysis approach. Adherence to the predefined PROM frequency (completed PROM assessments within the predetermined frequency) and the agreement between the DAS28 course and PROM values (Rheumatoid Arthritis Disease Activity Index-5 and the Rheumatoid Arthritis Impact of Disease (RAID)) were quantitatively assessed using descriptives. Results Forty-seven patients participated, most of them diagnosed with rheumatoid arthritis (n=38, 80.9%). Three themes were identified: knowledge about and insight into the disease (activity), patient–professional interaction and functionality of the program. Mean adherence to the predetermined PROM frequency was 68.1%. The RAID showed the best agreement with the DAS28 course. Mean participation time was 350 days. Conclusion Patients were predominantly positive about online self-monitoring. They indicated that they gained more knowledge about their disease, felt less dependent on the healthcare professional and valued the insight into their long-term disease course. Barriers were mostly related to ...