INTRODUCTION: Osteoarthritis of the trapeziometacarpal joint (TMJ) is a common condition causing significant disability. Conservative treatments include intra-articular steroid injections. PATIENTS AND METHODS: This clinical, observational study prospectively reviewed the longevity of benefit of steroid injections into the TMJ. Eighty-three patients were recruited with a median age of 62 years and injected with steroid and local anaesthetic under radioscopic guidance. They were followed up until the analgesic effects ceased with a questionnaire including visual analogue scores. RESULTS: Two-thirds of patients were improved at 2 months, with nearly half having a 3-month improvement. One in six patients had a 6-month benefit, with some patients still improved 2 years after injection. Previously injected patients had a reduced duration of benefit compared to their previous injection. Severity of osteoarthritis did not affect the injection efficacy. CONCLUSIONS: Based on this study, we recommend steroid injections in all degrees of TMJ osteoarthritis.