Defects in neuromuscular transmission suggestive of myasthenia gravis have been found in association with a wide variety of disorders, including hyperthyroidism,1-8 myopathies,9-10 lupus erythematosis,11-12 malignancy,13-15 and polymyositis.16 A similar relationship has been reported in various neuropathies, viz., poliomyelitis,17-19 syringomyelia,1,20 amyotrophic lateral sclerosis,2,16,18,21 and a variety of other conditions affecting the anterior horn cells22; however, in none of these cases did myasthenia gravis appear as the primary disease. This report is a study of a patient with apparent myasthenia gravis who developed striking resistance to conventional therapy, who ultimately proved to respond in part to repeated courses of "rest" therapy with curare, and who late in her illness showed unexpected evidence of motor neuron disease. Report of Case During November, 1955, it was noted that the patient, a previously healthy 12-year-old girl, was unable to smile, and that the corners of