Abstract Objectives Treatment non-adherence is more frequent among difficult-to-treat (D2T) than among non-D2T RA patients. Perceptions of non-adherence may differ. We aimed to thematically structure and prioritize barriers to (i.e. causes and reasons for non-adherence) and facilitators of optimal adherence from the patients’ and rheumatologists’ perspectives. Methods Patients’ perceptions were identified in semi-structured in-depth interviews. Experts selected representative statements regarding 40 barriers and 40 facilitators. Twenty D2T and 20 non-D2T RA patients sorted these statements during two card-sorting tasks: first, by order of content similarity and, second, content applicability. Additionally, 20 rheumatologists sorted the statements by order of content applicability to the general RA population. The similarity sorting was used as input for hierarchical cluster analysis. The applicability sorting was analysed using descriptive statistics, prioritized and the results compared between D2T RA patients, non-D2T RA patients and rheumatologists. Results Nine clusters of barriers were identified, related to the healthcare system, treatment safety/efficacy, treatment regimen and patient behaviour. D2T RA patients prioritized adverse events and doubts about effectiveness as the most important barriers. Doubts about effectiveness were more important to D2T than to non-D2T RA patients (P = 0.02). Seven clusters of facilitators were identified, related to the healthcare system and directly to the patient. All RA patients and rheumatologists prioritized a good relationship with the healthcare professional and treatment information as the most helpful facilitators. Conclusions D2T RA patients, non-D2T RA patients and rheumatologists prioritized perceptions of non-adherence largely similarly. The structured overviews of barriers and facilitators provided in this study may guide improvement of adherence.