OBJECTIVE: To adapt a United States-developed Overactive Bladder (OAB) economic model for use in the United Kingdom (UK). METHODS: A cost-offset economic model was developed in the US to estimate the cost-effectiveness of tolterodine (Detrusitol) and oxybutynin (ex. Ditropan). The economic model was adapted for the UK market by changing the medical treatment algorithm and collecting costs based on the UK-specific data. The percent of successfully treated patients was derived from the clinical efficacy adjusted by the annual persistency. RESULTS: The average total cost per patient for twelve months of treatment for oxybutynin is £226 and £502 for tolterodine. The percent of successfully treated patients after one year is 9.5% for oxybutynin and 36.4% for tolterodine. The average cost-effectiveness, expressed as cost per successfully treated patient, is £2377 for oxybutynin and £1395 for tolterodine. CONCLUSION: Although the efficacy of oxybutynin and tolterodine has been measured as equal, the persistency is over three times higher with tolterodine. While the cost of therapy for tolterodine is higher than oxybutynin, the cost-effectiveness of tolterodine is superior. These results were similar to the US-based model, but driven by the different treatment approach to OAB in the UK.