We prospectively evaluated the frequency, severity, and radiologic features of swallowing abnormalities following Botox treatment of spasmodic torticollis. We performed both clinical and radiologic evaluations of swallowing before and following Botox in 18 consecutive cervical dystonia patients receiving their first Botox treatment. Before Botox, 11% of the patients had clinical symptoms of dysphagia and 22% had radiologic signs of a peristaltic abnormality. After Botox, the signs and symptoms of dysphagia in these patients did not change, but an additional 33% developed new dysphagic symptoms and 50% of the patients developed new peristaltic abnormalities by radiologic studies. Complaints of swallowing difficulty were always associated with abnormal radiologic findings. Neither the total Botox dose nor Botox into particular muscles differed between those with dysphagia and those without.