A method is described for measuring rate of in vitro protein synthesis by hypopharyngeal glands of honeybees. No direct correlation was apparent between rate of synthesis and size of the acini of the glands. Full-grown glands of summer bees showed highly variable synthetic activity. glands of known nurse bees demonstrated the highest rates of protein synthesis. Winter bees with completely filled acini showed reduced activity, but protein synthesis increased in spring when brood rearing started.