This observational study assessed functional ability in patients treated with modified-release prednisone under conditions of normal clinical practice. Patients treated with modified-release prednisone were observed over 9 months. The primary outcome measure was the change from baseline total score using the Questionnaire on Activity Status (QAS); total QAS score ranges from 0 (severely impaired) to 100 (completely unimpaired). Other measures included Visual Analogue Scale (VAS) from 0 to 10 (where 10 = full daily performance) and Health Assessment Questionnaire Disability Index (HAQ-DI). There were no restrictions on dose of modified-release prednisone or use of concomitant therapy. A total of 1,733 patients were included in the study, with valid observations at baseline and study end for 1,185 patients (thereof 74 % female, median age 59 years, median disease duration 5 years). Mean total QAS score improved significantly after 9 months of treatment with modified-release prednisone from 54.3 to 70.2 (p < 0.001). There were also significant (p < 0.001) improvements in all three QAS dimensions (occupational performance: 66.6-78.9; household duties: 55.6-70.9; leisure activities: 51.6-69.4), daily performance (mean VAS 5.1-7.0; p < 0.001) and mean HAQ-DI score (1.35-1.00; p < 0.001). Dose of modified-release prednisone was significantly reduced (from 5.0 to 4.4 mg/day, p < 0.001) and fewer patients required biological rheumatoid arthritis (RA) treatments, analgesia and gastroprotectants. Functional ability in patients with RA improved significantly from baseline after 9 months of treatment with modified-release prednisone. This observational study, conducted under daily-practice conditions, confirms the beneficial effects of modified-release prednisone shown previously in randomised controlled trials.