AIM: To observe the protective effect of rhIL-1β on pancreatic islets of alloxan-induced diabetic rats.METHODS: Protection of rhIL-1β on pancreatic islets of alloxan-induced diabetic rats (n = 5) was demonstrated with methods of immunohistochemistry and stereology. The concentration of serum glucose was measured by GOD method and that of serum insulin by RIA.RESULTS: The concentration of serum glucose increased but that of insulin decreased after administration of alloxan(150 mg/kg), and the volume density and numerical density of the islets were zero. In rhIL-1β pretreated rats,although the concentration of serum insulin decreased (from11.9±3.0 mIU/L to 6.1±1.6 mIU/L, P＜0.05), that of glucose was at normal level compared with the control group.As compared with alloxan group, the concentration of serum glucose in rhIL-1β pretreated rats decreased (from19.4+8.9 mmol/L to 12.0±4.0 mmol/L, P＜0.05) and the volume density increased(0/L to. 1/L, P＜0.05).CONCLUSION: rhIL-1β pretreatment may have protective effect on the islets of alloxan-induced diabetic rats.