The aim of this study was to evaluate the efficacy and safety of intramuscular (IM) administration of botulinum toxin type A (Dysport((R)), Ipsen Biopharm Ltd.) for the treatment of cervical dystonia (CD) and the long-term safety and efficacy of repeated treatments. During the randomized, double-blind, placebo-controlled phase patients were randomized to 500 units Dysport (n = 55) or placebo (n = 61). Efficacy assessments included the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) total and subscale scores, visual analogue scale (VAS) for pain, subject/investigator's VAS for symptom assessments. Patients completing the double-blind treatment could enter an open-label extension phase and receive up to 4 additional Dysport treatments. Dysport produced a significant decrease from baseline in mean (+/-SE) TWSTRS total scores compared with placebo at Week 4 (primary efficacy endpoint; -15.6 +/- 2.0 vs. -6.7 +/- 2.0; p < 0.001) with significant improvements sustained to Week 12 (p = 0.019). Dysport also produced significant improvements in TWSTRS subscale scores, VAS pain scores, and subject/investigator's VAS symptom assessments compared to placebo. The mean duration of open-label study participation was 51.9 weeks (range 3.9-94.0 weeks). During open-label treatment, all treatment cycles resulted in improvements in mean TWSTRS total and subscale scores at Week 4 post-treatment; greatest improvement was seen in cycle 1. The mean duration between treatment cycles was 15-17 weeks. Dysport demonstrated a good long-term safety profile; most adverse events were mild or moderate and typical of the known safety profile of Dysport in this indication. These results confirm that Dysport (500 units) is safe, effective, and well-tolerated in patients with CD.