Propolis is a glue, prepared by honeybees from plant materials to stick their hives on the beehive wall. It has gained popularity in Japan as a healthy drink and people believe that propolis can cure inflammation, heart diseases and even diabetes and cancer. We have evaluated the β-cell protective effect of propolis against the toxicity of streptozotocin (STZ) in rats. The water extract of propolis (PWE) completely protected β-cell destruction against STZ toxicity. The protective effect of PWE was found to be almost equal to that of nicotinamide. PWE also inhibited the interleukin-1 β (IL-1 β) generation from human leukocytes. The free radical scavenging activity together with IL-1 β and nitric oxide (NO) synthase inhibitory activities are thought to be the prime factors for the protective effect of PWE against STZ toxicity.