Abstract Background Myasthenia gravis is an autoimmune disease in adults. Myasthenia gravis in children and adolescents is uncommon and the disease can present as congenital myasthenic syndrome, transient myasthenia gravis or juvenile myasthenia gravis in this age group. Juvenile myasthenia gravis also have autoimmune pathogenesis as in adults. The purpose of this thesis is to study juvenile myasthenia gravis. Methods It has been done a retrospective chart review of patients with juvenile myasthenia gravis who have been at Rikshospitalet hospital between 1991 and 2011. Patients with congenital myasthenic syndrome or transient myasthenia gravis were excluded. In addition to this, a literature review has been done through searches in PubMed/Medline and some literature is obtained through reference lists in articles. Results The chart review included 17 patients with juvenile myasthenia gravis. The ages of the children and adolescents ranged from 16 months to 18 years at debut of the disease and the mean age was 13 years. The distribution of ocular and generalized symptoms at debut was almost equal. Until the follow up, 88 % developed generalized juvenile myasthenia gravis and 12 % had ocular juvenile myasthenia gravis. The studied group of patients was dominated by girls with a female:male ratio 2:1 in the prepubertal group and 4.5:1 in the postpubertal group. Conclusion Myasthenia gravis is an uncommon disease in childhood but it is important to know about it so that the patients can get the correct treatment which is effective. In a child with fluctuating muscle weakness it is important to think about this disease.