Freezing of gait ( FOG) is common in patients with Parkinson disease (PD) and responds poorly to medical treatment. Botulinum toxin A (BTX-A) injections into calf muscles decreased FOG in previous open-label studies. The authors conducted a randomized double-blind placebo-controlled crossover study of BTX-A vs placebo in 12 subjects with PD and FOG. No significant improvement with BTX-A was found using subjective and objective measures.