The clinical course of anti-muscle specific kinase-positive myasthenia in children has been little reported. Described here is the case of an 8 year-old boy who presented with ptosis and generalized weakness, which resolved within I month without any immunomodulatory treatment. This spontaneous remission lasted 6 years and was then followed by a relapse with bulbar symptoms. The patient was put on plasmapheresis; after initial benefit, symptoms worsened and serum antibody levels persisted. This case constitutes an example of the variability of the clinical presentation, course, and therapeutic response in anti-muscle specific kinase-positive myasthenia in childhood. (C) 2009 by Elsevier Inc. All rights reserved.