Objectives: Guidelines recommend intra-articular glucocorticoid injection in patients with painful hip osteoarthritis. However, intra-articular hip injection is an invasive procedure. The efficacy of systemic glucocorticoid treatment for pain reduction in hip osteoarthritis is unknown. This randomised, double-blind, trial assessed effectiveness in hip pain reduction of an intramuscular glucocorticoid injection compared with a placebo injection in patients with hip osteoarthritis., Methods: Patients with painful hip osteoarthritis were randomised to either 40 mg triamcinolone acetate or placebo with an intramuscular injection into the gluteus muscle. The primary outcomes were severity of hip pain at rest, during walking (0-10) and WOMAC pain at 2-week postinjection. We used linear mixed models for repeated measurements at 2, 4, 6 and 12 weeks for the intention-to-treat data analysis., Results: Of the 107 patients randomised, 106 could be analysed (52 in the glucocorticoid group, 54 in the placebo group). At 2-week follow-up, compared with placebo injection, the intramuscular glucocorticoid injection showed a significant and clinically relevant difference in hip pain reduction at rest (difference -1.3, 95% CI -2.3 to -0.3). This effect persisted for the entire 12-week follow-up. For hip pain during walking, the effect was present at 4-week, 6-week and 12-week follow-ups, and for WOMAC pain the effect was present at 6-week and 12-week follow-up., Conclusions: An intramuscular glucocorticoid injection showed effectiveness in patients with hip osteoarthritis on one of the three primary outcomes at 2-week postinjection. All primary outcomes showed effectiveness from 4 to 6 weeks, up to a 12-week follow-up., Trial Registration Number: NTR2966., Competing Interests: Competing interests: MK reports grants from Abbvie, grants from Levicept, grants from GlaxoSmithKline, grants from Arthritis Rheumatology, grants from APPROACH consortium, grants from Foreum, grants from TI-Pharma, grants from Pfizer; outside the submitted work. SMAB-Z reports grants from Dutch Arthritis Foundation, grants from Nuts Ohra, during the conduct of the study. Pending grants from Dutch Arthritis Foundation, at the Netherlands Organization for Health research and development, and EU Horizon 2020, outside the submitted work. Grants received from the Dutch Arthritis Foundation, Netherlands organization for Health research and development, Nuts-Ohra, and EU Fp7, outside the submitted work., (© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)