A 48-year-old man with hypertension, hyperlipidemia, and hypothyroidism presented to an outside institution with progressive bilateral lower extremity numbness and weakness. Nerve conduction studies (NCS) suggested acquired demyelinating polyneuropathy. Right sural nerve biopsy revealed mild chronic neuropathy, axonal degeneration, demyelination, and remyelination. He received monthly IV immunoglobulin (IVIg) and mycophenolate mofetil for a year. Due to worsening symptoms in the setting of lengthened IVIg dosing intervals, repeat NCS were obtained and showed disease progression. Monthly IVIg infusions were resumed for 8 years, during which his clinical and electrophysiologic findings stabilized. Treatment was subsequently stopped, and he initially remained neurologically stable off therapy.