We sought markers for predicting a favorable outcome of botulinum toxin A injected to the lower-extremity muscles of 26 children with hemiplegic or diplegic cerebral palsy. Clinical assessment preceding and 1 month following injection included gross motor function measure, a modified Ashworth scale, and evaluation of range of motion of knee extension and ankle dorsiflexion. Response to treatment was classified based on a parent questionnaire. The 19 children (73%) considered by their parents as being good responders were compared to the 7 (27%) considered as being poor responders. In the good responders, the preinjection Ashworth scale (spasticity) was significantly higher (P < .05) and gross motor function measure scores (function) were lower (P < .05). Sixty-eight percent of the good responders were nonindependent walkers compared to 14% of the poor responders (P < .05). There were no differences in age, type of cerebral palsy, and dose of injection. An Ashworth scale indicating increased muscle tone, lower gross motor function measure scores, and nonindependent ambulatory status were predictive for a favorable response to botulinum toxin A injections and can guide patient selection and expectations of treatment outcome.