Fatigable muscle weakness is the clinical hallmark of the human autoimmune disease myasthenia gravis (MG). Weakness of the oropharyngeal muscles produces dysphagia, which continues to be a major source of morbidity in MG. In this study we prospectively assessed 20 patients with myasthenia gravis who described difficulties with swallowing. Videofluoroscopic assessment showed disordered swallowing in all, with abnormalities in oral, pharyngeal, and, to a lesser extent, oral preparatory phases. Of the 20 studied, 7 aspirated, most of whom did so silently. Laryngeal penetration occurred in many more patients. The characteristics of dysphagia in MG are described and compared with other neurological disorders that can produce dysphagia.