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.