Twenty-one myasthenic patients were treated with high-dose daily prednisone regimen at Seoul National University Hospital from May 1983 to January 1985. Observations in relation to dosage, drug schedule, clinical responses, and sideeffects led us to following conclusions concerning the management of myasthenia gravis with steroid. In addition, factors influencing the result were considered. 1) Among 21 patients, twenty(95%) showed clinical improvement of variable degrees. 2) Significant improvement could be expected especially in male patients, in older patients, and in those with duration of myasthenia gravis less than 6 months prior to treatment. Performance of thymectomy or thymothymectomy, thymic pathology, and clinical grade at the time of therapy were not considered to affect the outcome. 3) Ten cases (48%) suffered from initial exacerbations, most of which occurred within the first four days of treatment. Steroid-induced crises developed in four cases with preexisting brittle or severe generalized myasthenia. 4) Period taken to show the initial response and the maximum improvement varied widely but majority of them occurred within 15 days and 70 days respectively. 5) Off-day weakness during the alternate-day schedule required special cautions and, if persitent, immediate return to daily schedule was desirable. 6) Thymectomy prior to steroid treatment was not always necessary but, when both regimens were scheduled together, preparation therapy with steroid thought to be more favorable. 7) Aside from initial exacerbations side-effects during the treatment were not remarkable, all of which disappeared with reduction of dosage.