Conventional electromyographic (EMG) guidance in botulinum toxin therapy can localize a muscle, but the amount of electrical activity is assessed only subjectively. We wanted to introduce a quantitative EMG criterion, according to which the decision for/against toxin application could be made. Turn/amplitude analysis (TAA) was applied to nine patients with severe paraspasticity (n = 5), right upper or lower limb spasticity (n = 3), or tetraspasticity (n = 1) before and after toxin administration. Muscles were selected for toxin application if both mean turns/second and mean amplitude/turn exceeded the level of 150. A mean Dysport dose of 116 mouse units (mu) (range 40-240 mu) was administered to each of the 26 muscles that met the EMG criterion. Thirty days after the injection, activities of daily living, pain, and TAA count improved in 89%, tone in 78%, and range of motion in 56% of the patients by at least 1 point on corresponding 5-point rating scales. TAA provides a useful EMG criterion for/against botulinum toxin application. Muscle selection according to this criterion leads to a significant subjective and objective toxin effect. TAA is a valuable tool to determine the benefit of single and subsequent botulinum toxin injections in the treatment of spasticity.