Insulin secretion plays an essential part in the modulation of glucose homeostasis. Pancreatic beta cells are extremely sensitive to small changes in the concentration of glucose, peptides, hormones and fatty acids and insulin secretion is stimulated in response to these factors. The measurement of insulin secretion from isolated islets with either initiators or potentiators is a useful tool for investigating their efficacy in vitro without using cell lines, which can be subject to modification. Static islet incubation is a fast and powerful tool for the investigation of dose-response curves in response to insulin secretagogues, while islet perifusion experiments are useful for the investigation of the kinetics of insulin secretion. These two methods for measuring insulin secretion from isolated rodent islets of Langerhans are described in detail in this chapter.