PURPOSE: We assessed the cost-effectiveness of botulinum toxin A injection compared to anticholinergic medications for the treatment of idiopathic urge incontinence. MATERIALS AND METHODS: A Markov decision analysis model was developed to compare the costs in 2008 U. S. dollars and effectiveness in quality adjusted life-years of botulinum toxin A injection and anticholinergic medications. The analysis was conducted from a societal perspective with a 2-year time frame using 3-month cycles. The primary outcome was the incremental cost-effectiveness ratio, defined as the difference in cost (botulinum toxin A cost--anticholinergic cost) divided by the difference in effectiveness (botulinum toxin A quality adjusted life-years--anticholinergic quality adjusted life-years). RESULTS: While the botulinum strategy was more expensive ($4,392 vs $2,563) it was also more effective (1.63 vs 1.50 quality adjusted life-years) compared to the anticholinergic regimen. The calculated incremental cost-effectiveness ratio was $14,377 per quality adjusted life-year, meaning that botulinum toxin A cost $14,377 per quality adjusted life-year gained. A strategy is often considered cost-effective when the incremental cost-effectiveness ratio is less than $50,000 per quality adjusted life-year. Given this definition botulinum toxin A is cost-effective compared to anticholinergics. To determine if there are situations in which anticholinergics would become cost-effective we performed sensitivity analyses. Anticholinergics become cost-effective if compliance exceeds 75% (33% in the base case) and if the botulinum toxin A procedure cost exceeds $3,875 ($1,690 in the base case). For the remainder of the sensitivity analyses botulinum toxin A remained cost-effective. CONCLUSIONS: Botulinum toxin A injection was cost-effective compared to anticholinergic medications for the treatment of refractory urge incontinence. Anticholinergics become cost-effective if patients are highly compliant with medications or if the botulinum procedure costs increase substantially.