Imino sugars are carbohydrate-like alkaloids largely characterised over the last ten years that function as glycosidase inhibitors as they mimic the sugar moiety of the natural substrate. They have been reported to have immunomodulatory activity and the purpose of this study was to identify and characterise such activity. The ability of over sixty imino sugars to modify macrophage/dendritic cell cytokine production was analysed. The immunomodulatory activity of two imino sugars MNLP 462a and MNLP 24 with pro-inflammatory activity was studied in depth. They were found to upregulate in vitro macrophage IL-12 production and dendritic cell IL-12 and IL-2 production as well as co-stimulatory molecule expression particularly CD40, but in addition CD80 and CD86 on dendritic cells.