Insecticidal properties of protease inhibitors have been established in transgenic plants. Possible effects of these inhibitors on beneficial insects like honeybees (Apis mellifera L.)need to be assessed. Soybean trypsin inhibitor (SBTI) was fed to newly emerged caged bees at 3 different concentrations (0.1%, 0.5% and 1%) in pollen. Hypopharyngeal gland protein content and gut proteolytic enzyme activity was measured after 7 days. Mortality rates and longevity were also measured. Significantly less amounts of protein were detected in the hypopharyngeal glands of the bees fed with inhibitor at 1% concentration when compared to other treatments. Casenolytic activity (total midgut proteolytic enzyme activity) was found to be significantly low in case of bees fed with 1% inhibitor. Bees fed with inhibitor at 1% in pollen had significantly reduced life spans.