Seventy-six consecutive patients with cervical dystonia. (CD) treated with botulinum toxin were assessed with the Tsui rating scale, the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS), and a global scale of improvement. Tsui, TWSTRS, and TWSTRS subscale scores all showed significant improvement. Tsui and TWSTRS score reduction rates correlated significantly with each other, and each correlated with the global scale. Analysis of these scales and TWSTRS subscales indicates that an objective scale of severity such as either the Tsui rating scale or TWSTRS severity subscale used in conjunction with the TWSTRS pain subscale adequately assesses improvement of CD following treatment with botulinum toxin.