Data from the available randomised trials suggest, but do not prove, that periurethral injection of established manufactured bulking agents results in subjective and objective short term improvement of symptomatic female stress urinary incontinence in adults. Future recommendation as a first line treatment would require evidence of patient benefit and cost-effectiveness from randomised trials involving placebo and conservative treatment arms. Future studies should also record long-term outcome and monitor for delayed particle migration. Injection therapy is probably inferior to surgery but a long term comparative study against a single standard procedure (Burch colposuspension) is required to prove this. It is recommended that phase III studies of newer agents will not be worthwhile until the aforementioned trials have been performed and a rationale for the use of injection therapy decided. For women with extensive co-morbidity precluding anaesthesia, injection therapy may represent a useful option for relief of symptoms for a 12 month period although 2 or 3 injections are likely to be required to achieve a satisfactory result.