In multifocal motor neuropathy (MMN), little is known of the long-term effect of human immunoglobulin (HIG) infusions as a maintenance therapy. We report a patient who improved after an initial HIG infusion of 2 g/kg and continued to improve both clinically and electrophysiologically during maintenance HIG treatment consisting of one infusion of 0.4 g/kg every week. Our findings suggest that maintenance HIG therapy may lead to further improvement of MMN, and that more frequent HIG infusions at a lower dosage may be more effective.