Acquired myasthenia gravis (MG) is quite well known to be caused by the autoimmune mechanism. In addition, there are some opinions that MG is heavily associated with HLA-B8 in the Caucasians and HLA-B12 in the Japanese. To asses the association between human leukocyte antigens(HLA) and Korean myasthenic patients, the authours studied the HLA types in 30 myasthenic patients and 100 healthy controls. The results were as follows; The frequencies of HLA-Bw46 and DRwlO were found to be high in Korean myasthenic subjects compared with those in normal population. But there was no statistical difference in the prevalence of HLA type between myasthenic patients and control population. And we further analysed those data in view of sex, age of onset, clinical severity, and thymic pathology to know close association of any other HLA types with particular myasthenic groups. The HLA-Bw52 showed significant association in ocular myasthenic patients, the Bw46 in generalized myasthenic patients, the A30, B14 in severe generalized myasthenic patients. And HLA-B39 showed close association in myasthenic patients with thymoma, compared with normal controls. However the authors could not find any significant associations with reference to the sex, age of onset compared with those in normal controls.