Post-polio syndrome (PPS) is characterized by new muscle weakness, atrophy, fatigue and pain developing several years after the acute polio. Some studies suggest an ongoing inflammation in the spinal cord in these patients. From this perspective, intravenous immunoglobulin (IvIg) could be a therapeutic option. We performed a double-blinded randomized controlled pilot study with 20 patients to investigate the possible clinical effects of IvIg in PPS. Twenty patients were randomized to either IvIg 2 g/kg body weight or placebo. Primary endpoints were changes in pain, fatigue and muscle strength 3 months after treatment. Surrogate endpoints were changes in cerebrospinal fluid (CSF) cytokine levels. Secondary endpoints were pain, fatigue and isometric muscle strength after 6 months. Patients receiving IvIg reported a significant improvement in pain during the first 3 months, but no change was noted for subjective fatigue and muscle strength. CSF levels of tumour necrosis factor-α (TNF-α) were increased compared with patients with non-inflammatory neurological disorders. In conclusion, in this small pilot study no effect was seen with IvIg treatment on muscle strength and fatigue, however IvIg treated PPS patients reported significantly less pain 3 months after treatment. TNF-α was increased in the CSF from PPS patients. The results are promising, but not conclusive because of the low number of patients studied.