We present a case of prolonged resolution of stroke-induced trismus after botulinum toxin A treatment in a 9 1/2-yr-old boy. The patient had an idiopathic right posterior fossa hemorrhage with resultant spastic quadriparesis, ataxia, dysarthria, and dysphagia. He developed right-sided trismus with only fair response to stretch. Several months after discharge, the patient had worsening trismus with an interincisal distance of only 0.4-0.7 cm and difficulty with oral hygiene and eating. The patient was treated with botulinum toxin A to the masseter muscles with minimal response. Four months later, he received botulinum toxin A to the bilateral masseter and temporalis muscles and to the right medial and lateral pterygoid muscles, with more improvement. His third and last botulinum toxin A treatment was to the bilateral masseter, temporalis, lateral, and medial pterygoid muscles in larger doses. He had an excellent response, maintaining an interincisal distance of 2.5 cm 1 yr later, with significant improvement in speaking and chewing.