- OBJECTIVE: Morning stiffness is a common and clinically important symptom in patients with rheumatoid arthritis (RA); however, it has not performed well as a classification criterion, perhaps due to poor definition. This qualitative study was carried out to identify the characteristics of morning stiffness through the self-reports of patients with RA in order to develop a new patient centered definition. METHODS: Personal interviews with 24 patients with RA were analyzed independently by 2 reviewers using a grounded theory approach. A mail-out questionnaire was used to validate the information summarized from the interviews. RESULTS: These findings resulted in the following definition of morning stiffness in RA: slowness or difficulty moving the joints when getting out of bed or after staying in one position too long, which involves both sides of the body and gets better with movement. CONCLUSION: This new patient centered definition of morning stiffness may allow more precise classification of patients with RA.