The maintenance effect of low dose, short duration intravenous immunoglobulin (IVIg) therapy (0.3gm/kg/day for one day) is reported in a patient with myasthenia gravis. The patient had had a progressive course of diplopia, generalized muscle weakness and bulbar symptoms in spite of anticholinesterase agents and steroid therapy for two years. She received a course of high-dose IVIg infusion (0.5 gm/kg/day) for five days, and the symptoms disappeared in few days. However, they recurred 13 months later. Because of the high cost of high-dose IVIg, a trial with 0.3 gm/kg/day IVIg for 1 day was initiated. The clinical neurological manifestations improved within a few hours, and this made natural fluctuation unlikely. She received 4 courses of 1 day, low-dose IVIg therapy during the follow-up period of two years. The beneficial effects usually maintained for two to six months. She was symptom free and had no side effects. The report suggests that low-dose IVIg can be an alternative way, at least in some patients when there is consideration of economic benefit and convenience, compared with high-dose IVIg in the treatment of myasthenia gravis.