Intravenous immunoglobulin (IVIg) is used for the treatment of a number of autoimmune neurological disorders. Whether different brands of IVIg or different lots of the same brand are comparably efficacious for the treatment of neurological disorders is not clear. To examine this issue we compared the efficacy of different brands and/or lots of IVIg in a cell culture model of immune neuropathy. We report that products examined were equally effective and there was no lot-to-lot variability in our experimental model. These findings support the notion that efficacy of different IVIg products is comparable in a standardized model.