Introduction Myasthenia gravis is an autoimmune disease that causes neuromuscular transmission disorder manifested by muscle weakness and fatigue, in particular predilection muscle groups. Most cases are mediated by T lymphocyte-dependent polyclonal antibody directed against acetylcholine receptors. Approximately 10–15% of cases are etiological associated with thymoma. AChR antibodies in serum are detectable in 80–90% of patients. Of the remaining seronegative MG forms are most commonly detected antibodies to MuSK (30–70%) and especially in thymoma antistriatal, antititin and antiryanodin antibodies. Some cases are associated with low affinity antibodies against AChR. Diagnostic and therapeutic procedures in medicine has recently developed in a fast rate. The goal of our observations was to assess how the reflected developments in the area of the approach to patients with this diagnosis affected our department and to try identifying risk factors leading to a more severe course of the disease. Patients and methods The study included 45 patients (27 men, 18 women) followed in our department from 2009 to the present. The diagnosis was established on the basis of history, clinical examination and EMG findings. In this retrospective study was used material available in our archives. Results We present a cohort of patients with myasthenia gravis diagnosed and treated in our department. In our patients the EMG findings correspond with the severity of the disorder. We found that the higher titers of the antibodies against AChR led to a more severe course of the disease. Conclusion Despite advances in diagnosis and treatment of myasthenia, this still represents a challenge for physicians due to the relatively variable course and clinical findings. The aim of our study was to refer to this variability and point out not full understanding the pathogenesis of myasthenia. We determined risk factors leading to a more serious course of the disease in our patients.