Botulinum toxin (BTA) is a safe and effective therapeutic tool for many neurological conditions but few studies have investigated its real cost in neurological practice. We evaluated the daily cost of botulinum toxin type A (BTA) treatment through a cost effectiveness analysis alongside a prospective study of BTA injections at a French University Hospital over a 2-year follow-up period. The data of 3,108 BTA injections performed in 870 adult patients presenting with dystonia, facial hemispasm, or spasticity were entered in the database. Patients were questioned at each visit about the subjective effectiveness of the previous injection. The daily cost of BTA treatment was calculated as the ratio of each session's cost (including all additional costs) to the duration of subjective efficacy. The subjective rating of efficacy duration was 17.3 ± 7.7 weeks for facial hemispasm, 15.4 ± 7.7 for blepharospasm, 14.3 ± 6.7 for cervical dystonia, 14.5 ± 7.8 and 14.1 ± 7.4 weeks for upper and lower limb spasticity, respectively. The daily cost of BTA injections was 0.57 ± 0.20 <euro> for facial hemispasm, 0.95 ± 0.30 <euro> for blepharospasm, 2.85 ± 0.86 <euro> for cervical dystonia, 3.38 ± 1.49 <euro> and 3.62 ± 1.81 <euro> for upper and lower limb spasticity, respectively. When associated costs were considered, the daily cost of BTA injections was clearly increased (45-93%) in limb spasticity or rigidity but remained only modestly increased (15-37%) in other indications. These results obtained in a large cohort of patients show that BTA treatment has a low daily cost for a long-lasting effect, with a daily cost/benefit ratio that greatly depends on the indications.