Multifocal motor neuropathy with conduction block (MMN-CB) is purely a motor neuropathy with progressive weakness that is characteristically caused by conduction blocks. Association with antiganglioside antibodies and a good response to immunomodulating therapies suggest an autoimmune etiology. In rare cases, MMN-CB has been reported as an adverse effect of infliximab, a tumor necrosis factor-α blocker. We present a case of MMN-CB due to infliximab in a 45-year-old man with psoriatic arthritis who was exposed to the drug for 2 years because of a delayed diagnosis. We emphasize the possibility of this adverse effect and the importance of detailed electrophysiological examinations, which is supported by a review of the literature.